I used a junior hacksaw blade (minus the pins of course) to complete the cutouts for the servo hatches.

Unfortunately the hatches for the LE flap servos have been position such that one corner of the hatch is actually epoxied to a wing spar. Since I didn't really want to saw through the spar, I simply checked the layout of the intended servo and linkage, and determined that the hatch need not be the full size of the square that Didier cut. So, I basically removed a small triangle (about 1" on each side) from the removable hatch area, and reglued the pre-cut skin in the area to be left attached.

I'm sure a pic makes the above gobbledeygook clearer: