what year is your corolla? mine is a 99 and it only took me 5 min. to change bulbs. I only took out 3 screws (one on the black cover, 2 on each side of the "shell?" of the cluster") you juss pull out the thing and in the back there should be 3 bulbs. Mine are "194", to take them out, you just twist them clockwise, and replace. I'm thinking from the top of my head, so wording isnt all too specific, but its about right.
I'm also trying to find a guage with the stock rpm tach found on the LE and S models. Dunno if it works, but my mechanic said it should, just depends on wiring.
Hope this helps