It's easy and doable: I have converted our Hilux and Geo Prizm (Toyota Sprinter) to power windows.
Items need: All new/use door window winders (no drilling required: Toyota did a great job by maintaining same mounting locations) Switches on all 4 doors arm rests and door panels (Panels are not really required, but arm rest is a must so you can mount the switch to arm rest and then arm rest to your door panel. I have use Hilux surf arm rests to install switches into my Prizm. Then wiring: You can use OEM wires or do your own wiring. I did mine with a 30A fuse directly off the battery so I can roll windows up and down without turning the ignition on.
How good are you with wiring? It is not difficult.
To make life easy, try to locate a complete wiring harness from a toyota car/truck/suv. All have the same wiring/wire plug (especially 1988 to about 2002)
