Depending on the style ailerons you want, It could be quite a bit of work. But its definitely possible to install them.

1 to 2 inch wide strip ailerons full span would be the simplest. Just hinge on the ailerons, adding to the wing chord. You'll want to use one servo for each side, and have the servos about 3 or 4 bays out from the center section. routing the wires for the servos and installing the mounting plates will mean cutting some covering from the bottom of the wing.

Sort-of scale style ailerons would mean the servos mount further aoutboard, and quite a bit more work to cut the aileron shape from the wings, making stub rib ends and installing the wood for hinging the surfaces. You'd be cutting the covering up enough that it might mean recovering the entire wing.