good point tigger, actually just searching around, it looks like there is a gear position sensor which gives different resistances to the ECU. tap the wire and then use a circuit like this:
http://www.bluegauges.com/gpi_stuff/gpi_schematic.gif
so then you'd have an led counter, 1 led on for 1st gear, 2 on for 2nd etc.
I think that would work...
I should probably invest in a manual for my bike first heh