I am not sure as I got all that information from searching for a lighting system to begin with I dont see why that system wouldn't work for a 12V batt. rather than a 6V Batt.
If you are interested I have seen this and heard good things about it as well....
12V Mini-Gen With Switch For Motorized Bicycle Lighting - eBay (item 400109306480 end time Jun-13-10 01:13:52 PDT)
If you choose to go that route please let me know how it works as I might get one for my next build.