depending on whats inside you might have to
a. change the bulb to a 6 volt and attach a battery
b. change the bulb/socket to 6 volt and attach battery
c. attach battery or 12 volt bicycle generator
it does say it can be easily changed to 6 volt if you wish.
Thats a cool looking light.
I'd light it up using three white light 10mm LEDs that use about 3 volts each, wired in series, and use a 9 volt battery.
Used with a small switch, this can make for an easy self contained unit, that puts out a good amout of light.
Then there is alway the used of a small LED flash light, using the LED cluster and the battery pack.
I have even used the whole small LED flash lights inside some of my headlights.
i converted a 12 volt incandesent tractor utility light to run off 2 superbright LED,s
i actually used the 12volt bulb , and put the LED,s in the back
it runs on 2 circuts with a DPDT switch ( low beam - 1 bulb off 2 AA,s at 3volts ) and ( high beam - 2 bulbs off a 9volt battery )
all the batteries are inside the light housing
here is a link to my thread on the motorbicycling site
Note that in general, car-type lights use a lot more current than what you can furnish with regular AA-type batteries, thus all the talk of re-wiring to LED's. I assume this is the case with motorcycle lights as well.