After you get the tranny out of the way it's a piece of cake
Pull the flywheel off, remove the plate with the rear seal in it, cleanoff the gasket , pop the old seal out. If there's any groove in the crank, get a repair sleeve for it so the new seal doesn't leak like a sieve.
you may need to file a chamfer around the edge to get it on.
put a little sealer around the outside of the new seal and set a board over it and whack it in to the plate from the back side ( where it curves in ) once in runs flat to that side set the old seal againse it and the board on top od that and whack it till the face of the seal is flush with the outer edge, make sure it is even all around or it will leak.
Go to Wendys and get a medium soda , drink it , then cut the rolled edge off the top of the cup. Grease the outer edge of the cup and set the cup over the end of the crank ( this will allow you to slide the new seal on without tearing it up or rolling the edge over
) Slap some sealer on the new gasket , set in place, and ease the seal over the cup and torque the bolts down, remove the cup and smile that you just save $90 on a special tool. when you put the flywheel back on use locktite generously on the bolts to seal the threads or you will have an oil leak .
Break out your dictionary of creative language for the process of stuffing the tranny back in