I'm not running the extang ones, I actually bought some 36" led strips I'll be installing once it's warm out. Yes you can tie them into the dome lights. Look at my footwell light mod found here
. The instructions found on post#3 are from the Mopar bed lighting kit and show you how and where to tie into the dome light circuit. I also have some pics of the tie in. I'll be using this very circuit to tie in my bed lights once winter goes away and I can get them installed.