Although most of this was written a while ago for iGO8, a lot of it will also apply to the current Primo. Unfortunately, it's going to a "trial and error" thing. Please post what you tried and how it resulted. Thanks.

http://www.navitotal.com/showthread.php?962-How-To-s-Tutorials-and-Tweaks

EDIT: If you have any questions about making things work for Primo, just ask here and we'll see what we can do.