Sparky,

Here's the way I would do it. It's not going to be exact, but it's pretty close. First, if your radio has a "sub-trim" feature, use that to move the servo into a postion that will allow you to trim the plane for level flight. Then, assuming the stabilizer and elevator have about the same surface area, measure the angle of deflection of the elevator used for level flight. Reposition the stabilizer to 1/2 the elevator deflection. This should allow you to fly level with the elevator and stabilizer in trim. Good luck.

Paul