If I'm not mistaken the CVO tip is attached to a ring with three screws, just like the ones you bought. What I don't know is how that ring is attached to your stock muffler can, since the parts catalog drawing doesn't show any fasteners other than the three for the tip. If you remove the three screws that hold your stock tip on and slide the tip off, how is the ring secured to the muffler can? If it's welded in place and not secured with screws, you could always grind the welds and remove the ring, then replace it with the accessory mounting ring. Depending on how deep the core is in the can, you may need to mount two rings back to back, drill the muffler for three holes to mount the ring to the muffler, then use the other rings holes to mount the tip.
Of course if the Fullsac core is flush to the end of the can like those in Dartman's photos you could just mount the ring like the ones in his photos once the original ring was removed.
Anyhow, where there is a will (and grinding tools and drills), there is usually a way.
As for the rings, they can be purchased separately.
P/N 65275-07 Attachment Ring
P/N 8146 U-nuts (3 per ring)
P/N 2225 Countersunk Screws (3 per ring)
P/N 9493 Socket Head Screws (4 per) for direct mounting to end of core
Jerry
btw, unless the core is significantly recessed in the can, I would personally just mount the new attachment ring to the end of the core with spacers and longer socket head screws versus drilling holes in the chrome can. You will be better able to tell what's going to be needed once you remove the original tip and ring.