Turn off dome/map light delayed on behaviour

[hedron]

It's in 6-2 of the manual. ( https://cdn.subarunet.com/stis/doc/ownerManual/MSA5M1113A.pdf ) It says this behaviour can be turned off by a Subaru dealer. I want to know how to do it myself. It's just a pet peeve of things doing things automagically, when I can simply turn the lights on myself if I need to do so.

So, how do I prevent the dome/reading light from automatically turning on when shutting off the car?

I have a 2011 Subaru Impreza 2.5L Premium, if that matters.