Ok, this is what i did when i bought the harness, track, motor, and amp from a guy with a '92 240 that had power windows.
What you need:
A roll of 10 or 12 gauge wire
10-12 gauge butt connectors
On the drivers find the black (ground), red/black (wire to make it move), red/white (wire to make it move), and white/back wires (power). Those are the wires for the power windows. Like this
Now on the passenger side find the red/black, red/white, and white/black, these are the wires for the passenger side. I cut all the other wires off because i didnt need them. Like this
Now, go back to the drivers side and fish the wires through the boot that goes through the door and the side of the car. Once you fish it through, find a good ground for the ground wire. Now from here, your gonna have to cut 3 wires of the 10-12 gauge wire long enough to go across the dash. Now for the power wire (white/black) what I did was twist the white/black wire and the 10-12 gauge wire together and connect it like that with a butt connector. On the other end of the butt connector I attached the fuse wire tap like this
Once you do that go to your fuse box and find a fuse like the cigarette lighter and take that out and put it in the fuse tap along with another fuse and put that in the spot of the fuse for the cigarette light.
Now for the other wires, connect the wires you cut to the red/black and red/white wire and fish them through to the passenger side.
On the passenger side now, fish the wires you have through the boot from the door to the side of the car. Now get the white/black wire and connect it to the wire that you connected on the other side with the white/black wire. Do the same with the other wires and your done.
The end product should look like this
Hope this helps you guys.