Some buggies have tubes glassed in under the fenders. Here is what mine looked like:
If you don't have them you have a few options.
1. You can flip the body over and glass in some tubes to run the wires in. The tubes can be made of almost anything. Vacuum (like your home vacuum) hose, flexible electrical conduit, cardboard...whatever.
2. I have also used small plastic tabs that you can get from a Home Center. They are designed to loop a zip tie through. They are about 1" square. I have taken the adhesive sticker off of them and epoxied them under the sides every 6" or so and used zip ties to hold the loom against the side of the buggy.
You can also run them inside or alongside the tunnel as well.