Hey Bob,
Like Marty, I have run square drive for years with the soldered on Octura collet on Sport and 67 Scale boats. Looks to me that you would have to remove the square drive collet on the stub shaft to get the cable out of the hull, I prefer the flexibility of making up shafts as I need them rather than having to measure them and send them out to have the bitter end squared.
I use a stand pipe oiler for the cable, and two roller bearings in the strut which I grease wilt a small pin point grease gun.
I have used Square drive collets and one end squared cables from Lenny Blake at www.rumracingproducts,com for years. Only other one I have used came from Elite (black one in the square drive options pic) I got their address from Marty's site but that was quite a while ago now. Aeromarine makes a square drive insert to replace the regular insert for the compression style cables, but it is made out of brass and I wouldn't think it would hold up. Would still require the tightening of the Aeromarine collet to hold the insert in place - I don't care for the additional moving parts. CHEERS !!! Bob