You are taking a chance of burning up the LEDs in the taillight as I believe the normal current limiting circuitry for the taillight is in the headlight. You might email Supernova and ask if what you want to do is possible. They are pretty good about answering email technical queries.
__________________
Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
Visit and join the Yahoo Geared Hub Bikes group for support and links.
http://groups.yahoo.com/group/Geared_hub_bikes/