Got this for my birthday, it's a Whelen Engineering LED flasher for emergency equipment. Totally programmable with I think 25 different patterns. I am powering this light and the trunk LED lights via a relay that's triggered by the brake switch. I had hooked just the trunk lights directly to the brake circuit, so that connection became my relay trigger. Then I grabbed 12-volts for the power side of the relay from the rear accessory tap. I made an aluminum adapter bracket and painted it black to mount the light where the reflector was. I like this low location, because what I didn't want was to completely blind a driver a few feet back. However, backing up a bit and simulating the lower position of a sitting driver in the average car, they catch the direct beam from the light. So I think that'll work quite well. This vid is short, sorry. It was longer, but the .AVI file became corrupted somehow so I had to trim it down quite a bit.
The unit is heavy-duty, designed for emergency vehicle application, totally waterproof but I sealed the hole on the back where the wires come out anyway, just to make sure.
Someone in another thread mentioned the Signal Dynamics brake light flasher gizmo.. I have one, but unfortunately its so old, it won't handle LEDs. So what I'm thinking of doing is hooking up a simple electronic flasher (Auto Parts, around $14 bucks) to the trunk LEDs only and have them flash too. They're not very bright and the flashing I think will catch the eye faster. I'm gonna leave the OE light alone.
I also installed a momentary switch under the seat, just wire tied up to an adjacent harness. This connects the power wire to the programming wire and allows programming a new pattern, should I wish to do that. I played with a bunch of 'em, I kinda liked this one.