Although I haven't done the Supra's master cylinder yet, I just got through doing my toyota truck which is the same unit. A word to the wise, don't buy the Cardone brand unit. These units are just not built properly, and after screwing around for 4 days and several units, none of them allowed the brakeline fitting to screw into the housing completely.
I finally went with a Raybestos unit, but paid quite a bit more than the $30 unit Kragen was offering.
As for the install, it's pretty straight forward. 4 bolts hold the unit to the booster, and 2 brake lines connect it to the brakes. You'll have to bleed the brakes when you're done, and I'd suggest using some good dot4 fluid.
On average, it'll probably take you about 3 hours total without rushing. If you were in cali, I'd let ya borrow my Motive auto bleeder and cut your time down to about 2 hours!!!