Gstan,
Ok, here's what you do. First of all refer to the attached diagram. This is what we will use to make strain reliefs for the antenna. You will need two of them. All they are is arms on servo control horns that have been cut off of the control horn. First set up your exit in the fuselage, in this case we'll use the bottom of the fuselage. Drill a hole for the antenna to exit from. Mount and secure your receiver in place. We'll use the first strain relief on the inside of the fuselage. Run the antenna wire through one hole of the servo arm and then back out through the other hole in the servo arm. You'll need to place it so that when the antenna wire exits the fuselage the strain relief will pull against the inside of the fuselage and stop, this way there is no way for the antenna to pull on the actual receiver. This will keep damage from occuring to the receiver. Now run your antenna back along the bottom of the fuselage. If you have a tailwheel on this plane you can use that as an anchor for the rear of the antenna. If not you'll need to set a screw into the rear of the fuselage to anchor the antenna wire to, yes you can use a pin instead of a screw. Now use the second control arm and run the antenna wire in one hole and out the other (see diagram). Use a rubber band on the last servo arm hole to attach the antenna wire to the tail wheel assembly or screw you set to anchor it. This should pull against the strain relief in the fuselage and keep the antenna wire pulled snugly, and keep it in place. If you have any extra wire extending past this second strain relief just let it hang out past the second strain relief, it won't hurt anything. Personally, I use a small spring to hold the wire snug because fuel residue can eat away at a rubber band. Look at the second picture and you can see how I anchor my setups.

Hope this helps

Ken