I was pondering this same problem a while back.
You could use some cast, socket type, steel/stainless steel drop outs. Turn some spigots, one end to fit into your carbon tube and the other to fit in and braze to the drop out socket.
You can get these from Ceeway but they are aluminium and look a bit cheap and nasty from the photo's. Havent seen them in the flesh.
I think if you want Titanium you will be making them yourself, starting from scratch.