Help with wiring custom front signals

[KILNA]

I tried them with the third lead hooked directly to the battery's 12v and they worked properly without speeding up the blink. I just don't want to hook it directly to the battery since I'm sure it'll slow-drain it. Since the indicators are LED's they'll certainly draw less, but I know giving 12v to the third lead solves the problem, it's just a matter of where to get the juice from.

Also, I want to avoid having to route wires all the way back to the cabin of the vehicle if possible, since I'd have to find a spot to poke through the firewall, it'll look ugly and I know there's gotta be a good place to tap somewhere in the front of the car.

Thanks