Both the comptip and the all-aluminum mast use the same method of locking the sail up. They both use a hook-and-ring. The difference between the two is that with the all-aluminum mast, there was a "flap" that came down over the hook which would keep the ring from engaging when lowering the sail. Unfortunately, the flap made getting the ring to hook difficult.
The comptip masts no longer have the flap. You can not install a comptip hook on an all-aluminum mast because the profile of the tip of the comptip mast is different than that of the all-aluminum mast - it's tapered, so the hook will not fit. You can however, simply remove the flap from the hook on your all-aluminum mast and thus achieve the same thing.

sm