There's a couple of good threads around here already about rear wiring or setting up a crane stock.
Basically you can either run the wires along the outside of the receiver stub (at the 6 o'clock position). Between the stub and the stock pipe...if there is a channel cut into the stock pipe. You may need to file down the stub so there's enough room.
You can cut up into the receiver stub and run the wires inside the stub and through the stock pipe that way.
The first way is cleaner, neater and less work...but if you don't have a stock pipe with the channel, you're out of luck.