Simplest way if it's the same voltage, you have 6 LEDs on your dash hooked up to each individual gear, you need to set up 6 LEDs with resistors so you don't blow your LEDs.
That's what Matt@Tyga said could be a easy one to do.
I'll have a look into the wiring digits. I already cut the speedo off the bike and made up a dash with EGT's and a Digi Temp gauge so there is room for some gear lights. Probably sounds better than it is. Function over looks.
Cheers nxrsr20.