I need to determine the easiest way to get power from my keyless entry system without hacking the wiring too much.

My situation is that I have installed an android based radio/navi unit. Once I turn on the key, it takes about 20-25 seconds to boot. I want to install a relay that will provide power to the radio when I unlock the door via keyless entry. I have found the relay that will handle that. It will send power to the headunit (1) when the key is on or (2) for 2 minutes when power is supplied to a second terminal on the relay.

I am looking at options of using the door lock actuator or dome light as the trigger, since these cycle when the door is unlocked by the key fob. Has anyone done anything similar and know if there is a relay or other connector which is easily accessible to send power when I unlock the door, so I don't have to cut into any wire harnesses?

Thanks,
John