You're partly correct. You can use a T5 from an S10, but what they should have told you is you'll need to get a V8 camaro gearset and install that in your S10 T5 donor. This allows the S10's optimal shifter location for a pick up truck; along with the ability to use the cable operated speedo instead of a VSS; and you get the proper ratio for a V8 vehicle with something around a 3.42 or 3.55 rear gear.
Dave Reed (reed0380 on here) builds a lot of these "hybrid" S10/V8 camaro T5's and he'll also sell you the parts. I believe a new one is in the 1200 dollar range from him and others, compare that to the 2000-2500 for a new TKO or ultra-wide ratio 4spd.