your best bet might be to get a haynes repair manual. Thats what i did when i got my reverse glow gauges. You can pick one up at like advanced auto or auto zone for $10 i think. Its a handy to book to have if you ever plan on doing other mods as well.
i jsut put mine in my gen 3, took about an hour and half, u gotta pull out all this s***. but make sure to reconnect ur battery when u are putting the gauges in, so u can make sure it matches up. got v8sho.com they got a how to guide