Yep, what Fred said. If you choose the correct size aluminum footing it should just barely have enough room to slide onto the carbon shaft, then the insert will stop it from sliding off. If your inserts are already glued in, not to worry. Just take the nock out, strip the fletching off and slide it on from that end, and I use super glue around the end of the shaft where the aluminum footing will sit. Just be careful not to get any inside the threaded insert, or you'll have a heck of a mess on your hands.
Forgot to specify, the insert is glued into the carbon shaft and not the aluminum footing, the footing slides down on top of the insert and that's where you want it to stay.