I'm pretty finicky so I screwed into the dash using standard self tapping screws approx. 2 1/2" in length. It will enable you to get a really tight fit along all the edges, no gap and in fact, as the Pod pushed down on the dash, it trims it off nicely as it cushions around the pod.
Then again, I cut my dash, Dremeled and gouged a huge hole to fit my OEM screen and pod. The dash is made of some compressed foam substance. Probably very light in weight and really easy to dremel and screw into.