hairdryer, patience and fingernail, its probably going to come off very slowly and in pieces just like when you debadge a car, the only problem is the textured dash is harder to get "completely clean" than say your paint.
Once you have the residues left, Goo Gone or WD40 on a rag will help, again some heat will help loosen the adhesive. Once you have it all the way gone, any "ghosting" or different coloration to the dash can be corrected with a non-caustic dash cleaner.
I use Einzsett Deep Plastic Cleaner for cleaning of dash, interior, leather seats etc, this should finish up to give you a nice even finish to the dash. Then I use Einzsett Cockpit afterwards as a dash protectant, the combo should have everything looking great after you get the adhesive out of there!
Link here for both -
http://www.detailersdomain.com/1Z-ei...Kit_p_656.html