How to display an “Out of Page” (PopUp) ad from Google DFP on a Drupal 6 site?

Question

Been beating my head on this for a while now. We've recently set up Google DFP for small publishers to use with a Drupal 6 site. We use the google admanager module to display the ads properly throughout the site using blocks.

I'm trying to create an out-of-page (ie. popup) for the front page.

In the past with OpenX I accomplished this by putting popup code in a block on the page. But this hasn't seemed to work yet with DFP.

Admittedly I'm still learning the in's and out's of the system, but have tried a few different ways now to no effect.

I've tried this: https://support.google.com/dfp_sb/answer/3370474?hl=en but haven't gotten it working yet, and not sure it will even be suitable for general use by staff who submit ads.

Would love to hear how others are making this work.