The tough part is going to be getting the clear to stick to it. Primers are what makes topcoats and clears stick the the substrates, either mechanically or chemically. In order to put a clear topcoat on, you'll need to put a clear bonding agent on first. I worked for PPG long ago and we sold a product called DSX1900 Bonding Clear. Check with a body shop or better yet, paint supplier and see if they have a product like that to use on your dash. You'll need to either take the dash there, or get the plastic identifier code (its a stamped code on the back, usually two letters, that identifies the type of plastic) so they know what its made of and what kind of paint is compatible. Some paints will actually melt some plastics. Good luck.
