I have found it best to take the tape off the cover plate as its very awkward to get in between the horns once in position, Put the cover plate on the horns and move up the horn out of the way of the area to be inserted into the wing/tail, Load the slots with a microballoon mix until nearly flush with the surface, push the horns into position and wipe away the excess glue with a rag or cotton bud wetted out with lighter fluid, put your alignement template in position and check all is true and to your liking, put some glue back onto the roughened surface under the area to receive the cover plate and lower into position, with a cotton bud wipe away all the excess glue from around the edge of the cover plate and between the horns and recheck the position of your template, leave to set fully.

Mike

EDIT: I forgott, in the time honoured traditions of all instructions: "repeat above three more time to complete".