You can get 2 lengths of music wire - 1 the diameter of the TE of the wing that will contact the LE of the aileron - the other the diameter of the desired thickness of the TE of the finished aileron.
Put these down on a flat surface with the aileron stock between them. Hold all three in place (I use clamps on each end) then sand the top of the aileron stock down to the tops of the music wire. I use an electric sander with 80 grit sand paper but you can do it just with a hand held sanding block. Just before it hits the top of the music wire switch to 180 grit.
When done sizing the aileron stock mark and cut the hinge slots/holes before shaping the LE of the aileron. This way it's much easier to find the center of the aileron LE.
I have a sanding block I made on a table saw out of a piece of pine 2" square X 12" long with a V cut into it at a 45 degree angle.
This is what I use to shape the LE. You can do it at less of an angle and you can do it by hand if your careful and take yer time.
Hope this helps ya out.