I ran a piece of heavy monofilament fishing line through the holes I drilled on each side. Left plenty on either end. Taped each wire to the mono to pull it through.
Definitely only use 18 gauge wire. I found out color really doesn't matter, you can use all black. I pulled one wire at a time, soldered and heat-shrink tapped it.
Whole thread of tips here:
In bar wire tips thread
