I agree with syrups being a bad idea. Yes it would work, but a syrup is going to be concentrated. Compounding on this, Owly's syrup would not be just a simple sugar, and you cannot guarantee the sugar levels.
Owly has his own ritual/process and has worked out the kinks to work for him. Your mileage WILL vary. I would not recommend that method to someone starting out.
Another detail to note, adding the fermentables to the bottle is not a good choice either. You cannot know exactly how much is going into each one and you'll have differing carbonation levels. "Yea I do, I put a teaspoon!" No you didn't, you just think you did.
Owly can get away with this for various reasons, which I won't get into because it's not a good practice.
So what would I say to do?
Use this to determine how much simple sugar to add at bottling for the desired carbonation levels:
http://www.brewersfriend.com/beer-priming-calculator/
When you are ready to keg, there is no need to prime:
http://www.brewersfriend.com/keg-carbonation-calculator/
In the bottle priming calculator you'll notice there are 3 options, Corn Sugar (dextrose), Table Sugar (sucrose), and DME.
Dextrose is the most simple sugar, it is glucose.
Sucrose is the next most simple sugar, it is (1) glucose and (1) sucrose.
DME is the most complex of the 3, it is a bunch of different things but mostly maltose (2 glucose) and a whole bunch of other stuff like flavor compounds, proteins, etc etc etc.
Dextrose will ferment out the cleanest with the least change in flavor. If you care about GMOs in your product, find organic dextrose. This can be bought at homebrew shops, or ordered online. I doubt you'd find it at the grocery store, but you never know.
Sucrose will take just a little bit longer to process by the yeast because it must be split first (inversion), unless you invert the sugar before hand. It won't change the flavor of the KT, but it could leave more residual sweetness due to the fructose content. Fructose is sweeter than glucose, and the yeast will prefer to process the glucose first, so if you refrigerate before they can work all the fructose, it could end up being sweeter than you expected. Depending on how much you used, even very cloying (means too sweet).
You can find this at the grocery, but usually not at the homebrew shops. This is what I use, I get the Domino brand because it is proudly Cane Sugar. If you get cheapo value brand sugar, you can bet it's probably GMO sugar beet derived.
DME is dried malt extract, it's concentrated beer wort that is dried to a powder. This is made from barley, and could be GMO barley unless you got an organic kind, or one from Briess Malting. I emailed them asking about GMO grain, the half-assed reply I got says they won't buy GMO grain. Before I digress, lets move on. DME will change the flavor of your KT; the amount you use determines how much of a change. If you're curious, try it! You may really like how it tastes. Maltose has to be split, like sucrose, but it breaks down into (2) glucose. DME (or LME which is liquid extract if you wanted) could leave some residual sweetness like sucrose due to other less fermentable sugars like maltotriose (3 glucose), and other longer chain dextrins, but their sweetness is less than that of fructose.
http://www.howtobrew.com/section2/chapter12.html
Yea that's great and all, but how the F do I do it, right? Right, that's what you asked.
Get out a small sauce pan (or whatever), put in 1/2 cup of water and the amount of your sugar choice.
Start off with enough sugar for 2.0 volumes of CO2. This will give you some carbonation, but not a gusher. If it's not enough, increase the volumes in the calc next time. Please don't start off at 5.0 unless you like sticky exploding glass. No seriously don't.
Bring this solution just to boil then cut the heat. It doesn't have to boil, you just need it hot enough to dissolve the sugar. It'll need to cool before you can use it. Now's the time to start your bottling process.
Get out all the bottles you're going to fill. Make sure they are nice and clean. No need to sanitize, since you're KT already has bugs in it, but you don't want to fill any that have dip spit or cigarette butts in them.
You're going to need another container to siphon into so you can evenly distribute the priming solution you just made. I use a bottling bucket because it is easy to clean and has a handydandy spigot. Siphon out the amount you want to bottle, leaving behind the starter for the next batch.
What if I don't have another container?
Well, then you have a few options. You could prime each bottle and siphon on top of it; the least consistent option. You could siphon to another container that you do have, like a pitcher or something you know the volume of and make your priming solution in batches tailored to that volume; not as consistent because you could get differing carbonation between batches. You could prime the fermentor. Not the most ideal because you'd be priming your starter too, which isn't necessarily a bad thing, but would provide the most consistent results for the situation; you'd need to calculate priming solution for the entire batch size, not bottling volume though.
Once the priming solution is cooled, add it to the volume of liquid in whatever container you went with. Mix it in well. If you're going to use a racking cane and hose, you'll need a hose clamp. If you still have time, stop by your local homebrew shop and get a bottling wand:
http://morebeer.com/products/bottle-filler-removable-spring-38.html
It'll make your life much simpler, and they don't cost much. They can be disassembled for easy cleaning.
Still using just a hose and clamp? That's fine, I started there too.
Make sure the clamp is set high enough on the hose so the end can reach the bottom of the bottles. Leave the clamp open while you start the siphon, then put slight pressure on the clamp to slow the flow down while you fill. If you don't, precious KT will come flying out the top and you'll have a sticky mess. Sam's Club sells a pair of bus tubs for like $11, they're great for containing spills and super easy to clean later!
When the liquid gets to the top of the bottle, shut off the flow and pull the hose out. This will leave you with just the right amount of headspace for carbonation. If you picked up a bottling wand, the shut off is automatic because it has a spring loaded valve in the tip :rockin:
Just cap and store at room temperature for a few days to a week. The time you need to let them sit depends on several factors, like what is room temp, yeast viability, and the type of priming solution used. Put one in the fridge after 4-5 days of sitting out, then a day later put another one in the fridge, and drink the one you had in there. Keep doing this until you find the number of days that works for your process and choices made.
If you find that you like how the bottle that sat for 10 days is carbonated and tastes, put the rest of your bottles in the fridge now, because they'll be 1 day behind that one! Now you'll know for next time how long to let them sit. If you change the amount of priming sugar used, you'll have to let them sit a little longer as not only will there be more sugar to process, but the CO2 produced needs time to dissolve into the liquid; which it doesn't want to do at room temps. Gasses will dissolve better in colder liquids, than warmer ones. So when the KT is warm, you've got some in solution, but the rest is pressurized in the headspace. If you open a warm one, you've just let out most of your gas.
I know that's a lot, let me know if I missed something.