I agree that the T5 is preferable, but a true overdrive has some nice features, like freewheeling (saves gas) and clutch-free shifting. Installation is a tradeoff. It's a bolt-in using stock clutch and throwout collar, and the standard 3-on-the tree will work. But with the T5 you don't have the issues of solenoid and governor wiring to contend with.
Just be sure you get the right T5. Some of the S10 versions have undesireable ratios - like a .86 overdrive 5th, hardly much help at all.
