Dwayne- sounds like you have a wing with a full vertical spar(it's not necessary, but some people do it). Getting leadout holes will be difficult. I got a small diameter soldering iron cartridge, about 10 watts or so. You'll also need an adjustable voltage power supply. I mounted the cartridge on a 1/4 in. hardwood dowel and soldered wires to it that run to the power supply. If you plan on doing this a lot you have to build a jig that will allow you to slide the foam onto the dowel to melt a hole until it reaches the spar. Then find a 5/16 in. diameter long drill, or solder a short drill into a piece of tubing. Feed it into the hole slowly until it hits the spar. Then work it in and out a little to dig through the spar. The you can continue melting the hole through to the root of the wing.
If you only have one to do, you can do a pretty fair job by marking the line to follow on the surface and feeding the melter through by hand.
This will be a real pain, no matter how you do it.