Remove current wingtip.
Use original wing tip as a template to locate the holes for the winglet root rib.
Place the composite (or aviation plywood) sheet the wing and trace the airfoil profile ahead of the aileron.
Remove the Composite sheet and use a template made using the winglet to trace the aileron portion of the airfoil. This will assure that the rib will fit the winglet.
Undercut the traced ribs about 1/16" so that they will fit in the winglet and the winglet matches the wing. This will require some sanding and fitting.
Screw winglet ribs to the wing using the cap screws and slide the winglet over the rib to check for fit. Make sure the aileron has enough clearance.
Carefully drill holes in the winglets to allow the Allen drive to pass through.
Remove the ribs from the wing. Bond the white foam to the ribs. Sand the white foam so that the winglet will slip over the foam.
Clear out the white foam around the screw holes and place a washers, cap screws, and brass tubes in place.
Cut the fiber glass sheet to shape and glue it to the white foam to prevent the cap screws from falling out.
Drill a 3/16" diameter hole through the fiberglass to allow the Allen driver to turn the cap screws.
Screw the ribs to the wings and re-test the fit of the winglets. Make sure you can remove the winglets with the Allen driver before gluing them in place.
Remove some foam between the fiberglass sandwich and some of the white foam around the rib for added epoxy bonding area. Be careful that epoxy can not penetrate the screws during winglet bonding operations.
Mask of the wing around the wing tip.
Put some grease on the screw threads. Screw the rib on the wing tip.
Put some epoxy and cotton flock slurry around the winglet rib and align the winglet on the wing. Clamp and tape the winglet in place while the epoxy cures.