Greg,
Here is a quick and dirty procedures you can try..
Under you Scripts settings, click on MASTER script and scroll down till you see "New AD Block", click on that and after the new Ad block appears under the default one.. ajust it's settings, then go to the template you want and add $GAB_ads[0] variable for the default and $GAB_ads[1] for the one you just created. Just add more as needed, just remember to increase X on $GAB_ads[X] as you ad new ad blocks.
That should do it!