I've done it before, I don't have pics though, but I can tell you how I did it.
Route your motor wires (18 gage) as per normal rear stock configuration. So from motor to rear end of the mechbox with one wire going underneath the pinion gear of your motor.
And run the trigger wires (20 gage or smaller) around the OUTSIDE of the mechbox, one on each side.
As I recall they don't fit in the lower reciever, so they run across the side of the mechbox and sit on the inside of the UPPER reciever once you slap the gun back together.
Once the mechbox is back in the lower reciever, the motor wires run out the back end just like they normally do, and the trigger wires have to drop into that area before they reach the end of the lower reciever, because the upper and lower have a lip that locks them together right at the back.
Now the tricky part is on some AEG's you MAY require some modification.
Some lower recievers have tabs that will prevent the wiring from going in. This spot is geographically directly under the back end of the spring guide. You may have to dremel in grooves to run the wires, no big deal, took me 5 minutes.
So once you get that out of the way, you have all 4 wires coming out the back of the lower reciever.
Things to watch for-
don't pinch the wires anywhere, especially around where the mechbox meets the lower reciever.
Take care installing the buffer tube so you don't crush the trigger wires, because they're thin and flexible they can easily get caught under there. Just hold them tight while you screwing the buffer tube back on.
Hope that helps, let me know if you need pictures and I'll try to get them done around 0900 ZULU