I've kegged tons of beers over the years, and really, it should be pretty quick and easy if you want to drink your kegged beer at any desired carbonation level.
First of all, look at the carbonation level that is desirable for your particular style of beer. Maybe it's 2.5 volumes, maybe 2.8 or whatever. Anyway, find out how much psi is necessary for the temperature of your beer. There's plenty of charts out there.
Of course, you want to make sure your beer is cold when carbonating.
Adjust the regulator for how much psi is necessary to achieve the desired volumes of co2, then simply shake the kegerator back and forth (with the co2 tank still hooked up). At first, you'll hear the regulator releasing co2 into the beer, and as you keep shaking, it'll slowly die down. Once it no longer releases any more co2 into the shaking beer, set the keg aside for several hours.
Let it just sit at that predetermined psi with the co2 tank and regulator still hooked up in the refrigerator or kegerator or whatever while the foam settles inside the keg. If you do that in the day, it'll be ready to drink and perfectly carbed by night.
Shaking will move any sediment around on the bottom and mix with the beer, but it's generally not a concern since most has been dropped out in another fermention vessel, and gets diluted so much anyway.
I've brewed lots of kegs for parties and used this method for carbonation to great effect. I would often bring the keg to the location early, put it in a cooler with ice (if I didn't have room to cool it beforehand) to cool it down, then just force carb it right there. It'd be ready to serve within 4-6 hours and perfectly carbed.
