I can't imagine copper crimps holding well enough.
Whatever you do, get the replacement cables on their way so your temporary fix only has to be temporary and as brief as possible.
You might take a small bolt and drill a hole in the shaft and then run a nut down on it to use as a cable clamp. Probably need two or three then cover with plenty of electrical tape to keep from scratching up the down tube.
Last edited by Iride01; 05-17-20 at 12:31 PM.