PMU Hold power to enable wing mirrors to retract

I'm currently in the planning stage of installing a PMU24 into my Celica GT-Four. after many revissions I think I'm pretty much there with my Inputs/outputs but the one thing I'm struggling with is I'm wanting to have the wing mirrors fold after I've got out the car and locked it.

The security system (Cobra 8165) has an output the goes to 12v when the system is armed (not sure how long for and it doesn't say in the manual and the car's in storage so can't realy test at the minute). The mirrors have their own factory control box which work on a 12v momentary switch to open them and the same push of the momentarty switch to close them. I can't control them directly through the PMU as the motors reverse polarity so would need a half bridge output and the control box for the mirrors (factory toyota) was £30 on ebay compaired to £300 for a ecumaster half bridge module.

Is there a way to keep the PMU running for a short period of time to let the mirrors retract then shut down? It's obviously got a permanant 12v feed on the stud so can it delay its shutdown after the switched 12v feed is removed?

I realise I could wire the 12v feed from the alarm to the mirror switch wire to retract the mirrors on arming the alarm but when opening the car up again the mirrors won't unfold without having the physically push the button.

Thanks in advance