Tools you'll need:
Wire cutter, wire splicer, small ratchet set, a flathead screwdriver just to help out, stuff to connect wires, the aftermarket radio harness ($15 autoparts store, electronics store, or car audio store) and the stock radio removal keys ($3 from a local autoparts store).
This should take you about two hours at the very most being careful, most of the time spent cutting the wires and splicing. This doesn't include the amp bypass, just instructions to help you with installing a new radio.
Sit around, watch TV, and splice together the wire set that comes with your new radio, together with the harness you just purchased.
Open up the dash. Pull out the ash tray, push down on the clip above the tray to fully take it out. Let it hang. Use the ratchet set to remove the two small screws on the side of the ash tray holder assembly. Pull that out. Now, gently, but firmly, start pulling the face assembly away. It might be easier if you put the steering wheel in a lowered position, as well as the shifter, if it's automatic. Make your way around the whole dash, watch for wire connections, such as maybe an alarm LED, and if you have 4x4, the 4x4 button cluster (disconnect this with the help of the screwdrivier). Hardest part will be getting this whole dash face over the steering wheel column. Use the "keys" to get out the old radio. Install the new one, with the harness easily plugging in to the factory wiring. The rest will follow!
Good luck!