Running a second winch controller is probably overkilling it. I'm not sure what you're trying to do here, but here's what I have in mine:
Battery to high-current switch (this isolates the winch) to winch power, controlled by standard box tucked away under the front and using a cable. It works, it's effective, but I do have to remember to take that controller with me.
An alternative would be to wire in a switch inside the cabin and run that out through the firewall and permanently hook it into the control box. A multimeter will show you what your current switch is doing and all you really need to do is emulate that with a switch in the cabin - you'll want a double pole "centre off" switch, so that it automatically returns to centre when you let go (turning off the winch).
This allows you to use ordinary wiring to manage it. The high-current switch should be placed very close to the battery. Jaycar sell one that has a removable "key" which isn't really needed if the switch is under the bonnet but does provide a little extra security in that the switch can't be accidentally turned on.