As suggested by the CSOB toolkit, it's not really tools you need, so much as bits and pieces. Be sure to read the tech note on the Pelican Parts web site. They have some nice ideas using threaded rod and sockets.
Replacing rear bearings was the very first job I did on my car. One of them was howling, and who knows how many miles it had on it in that condition. I got to the point where I had to drive it out of the trailing arm and it wouldn't budge - it was baked in place. I gave up, and called a shop to see what they would charge -- labor only - to do the job. It was in the $900 range. So I pulled the trailing arm, set it on an iron block, and wailed on it with a BFH. Finally broke loose. The other side was a piece of cake. Keep in mind that if you bremove the trailing arm, you'll need to have the alignment done.
Its pretty much a given that you will destroy the rear wheel bearings when you remove them. The important thing is not to destroy them when you put the new ones in ! Thats where all the tricky tips come in. You want slow, even pressure on the outer race of the bearing to pull it gently into place. Then equally even pressure to pull the stub axle into the inner race, without straining the bearing - pounding the stub axle in will not work !
The other thing to realize about the job is that you have to do a lot of work to get at the hubs. Axles need to be removed, so you'll need a special tool for the CV joints : NOT HEX, NOT TORX. Its 12-point, and it can be found at the local store if you try hard enough. And you'll need new CV gaskets. Once you get the CV joints loose, you still can't get the axles out of the way b/c of the exhaust. So count on pulling that. More gaskets. And you need to disconnect the shift rod. So there's a whole lot of steps involved.
Sorry if this part is obvious, but from your post I'm thinking you might have missed this : The 914 hubs don't have studs, they have drilled and tapped holes in them. The wheel is held on by bolts, not nuts. So the typical conversion is to drill 5 holes in the hub and press in studs. Then drill 5 holes in the rotor so it fits over the studs. Then the wheel fits over the studs, then nuts hold it on.
I've been reading up on this stuff, because I'd like to have a choice of wheels, but its frustrating how much $$ and
it takes just to end up with something that, in itself, doesn't have any affect on looks or performance (You gotta spend more $$ on wheels and tires for that.)