need to spec my infil for bg'sFollow

Depends on what kinda Inf you wanna play. I myself for BG1 with:
24th lvl Infiltrator:
15 envenome (bumped to 20 with items)
22 Stealth (bumped to 25 with items)
21 Crit Strike (gets you both Garrote and Perforate Artery)
15 Thrust (bumped to 20 with items, gets you Bear Tooth/BloodyDance chain)

As you can see, I am pretty much going Crit Strike/Envenome on mine, may switch this around at 40 with respec, but doubtful. He seems to be pretty viable so far.