Creating a Popup gauge

Anybody know how to make an XML gauge that pops up the 2D window of choice?

I've seen posts that say you can do it, but maybe there is a script out there or some code?

I want to do it for the RXP in 3D cockpits that don't natively integrate it. I tried putting the 530 in by Panel edits but it is covered over by 3d model stuff so the popup are doesn't actually work.