ops...^ i didn't read that very carefully
if you want to bypass the relay and not worry about the jumper, just put in a toggle and fuse, then:
i would think that all you'd need to do is pull out the oem wires and put in some heavier gauge stuff and solder all the connections possible. that should get the resistance down low enough that melting anything "shouldn't" be a problem. may be even a better ground too.