Dug up a bit of info on medicinal herb extraction and
and has a few techniques for THC extraction for baking, she uses mostly leaves but you can use buds too. Now, one of them is for butter, which wouldn't be useful here at all, the oil i'm a bit dubious of its usefulness to, think the best way would be a simple alcohol infusion.
Best part of that is you can use any kind of alcohol you like. If I was doing it I'd probably chop or grind what i'm putting in there, give it a couple days in a mason jar with some booze in, pick your poison, and strain it out really well then after I'd probably look for a safe and easy way to evaporate a bit of the booze off, esp if i was just goin with something like vodka. For oil extraction I've heard of using alcohol and boiling down until you're left with just the oil but they stress to never use gas stoves or open flame and to only have it at a very low boil. Both those make me a little nervous, i'd probably just put it on super low heat on an electric for awhile or better still, screw a piece of cloth in place of a lid on my mason jar and put it out in the sun.
Like others mentioned, not sure what ferment would do to it and if I was doin it i'd want the most bang for my buck so I'd probably wait until after fermentation and drop it in. If you prepare it sometime near the brew day you'd probably have plenty of time to slow-evaporate it like that.
Hope some of this could help and TELL US HOW IT COMES OUT!!! I'd really like to experiment with a single gal batch someday