I also plugged in an MCD 'ADD-A-SWITCH' circuit board to RX channel 5 (GEAR) and set up the TRAVEL ADJUST of Channel 5 (GEAR) to 125%. I can now turn on the front headlight by flipping the GEAR switch on then off. This doesn't seem to interfere with the MIXES using the GEAR channel (unless you leave the GEAR switch on!)
I'm going to add a Pico switch to channel 6 (FLAPS) so I can power down the tank by flipping the FLAP switch from the transmitter.

Hope this helps someone to set up their DX6i

Chris