I wouldn't inject him directly, I expect that would kill him. When I did it I had to remove the rock to get at his cave and pulled him out with some tweesers so he was out for a while. It really didn't take much just 5ml or so into the cave of the 1:50 oil:tank water mix and most of the oil had settled to the top right away, the cave also keeps it fairly localized so not much is needed. I would do a few ml then try to pull him out and into a net asap because he'll wake up fast, also make sure to kill all water flow a few min before. It is a bit hard to tell when they pass out because they don't move much to begin with when in the cave, mine was also under a ledge, and wasn't dosing into an enclosed space but just confined, so I just overestimated on my timming and dose to make sure I didn't have to repeat. Let us know how it goes!