Do you have a drill press or bandsaw. If so it makes the following pretty easy. First take a small block of hardwood and drill a hole the size you want vertically through it. Now, mark off the angle on one side parallel with the hole and shave off the lower edge of the block to make the surface that the hole exits through have the same angle as the aileron surface. Now, just locate the block so the bottom of the hole is over the point you want to drill at. Drill through the block using the block as a drill guide.