Well, I checked under the bumper for wires last night- none to be seen. Looks like I'll go the route Scott suggested and tap in from the tailight assemblies.
Scott thanks for the offer of more help. I'll do the dissassembly this weekend and shoot you an email if things don't look obvious. My currnt thoughts are how to route from the tailight assembly down to the bumper area. I suspect when I open it up there will be a hole somewhere.
Thanks again to all.