I've never torn out my mr-2 tranny, but I've replaced many in my rx-7 and one in my 912...both of which are absolutely nothing like an mr2's design.
from what I've heard around this forum, the clutch replacement is a pretty large task.. and given the design and layout of the engine and tranny... it's almost exactly like changing a front-wheel drive clutch.... if not the same process.. I've attached a link to give you a little more info than what my rambling can.
http://www.mr2-tech.com/bgb/mechanic...me2/clutch.htm
good luck