As a matter of fact, you can't.
I know, I just tried. The coat hanger cannot be soldered to a standard RCA connector with a 60 watt soldering iron. I had to use my propane torch, and of course I destroyed the dielectric in the connector. Even if I was sucfcessful in establishing a good connections, the stiffness of the hangers/wires in such close proximity would make handling it a problem and I'm sure a short would occur in short order.
Coat hangers do make excellent brazing rods though.