Brian:
I've had good luck painting the vanagon grill.  To be sure you don't encase
bug guts in your finished product, wash it, let it dry thoroughly, run over
the surface with some fine grit sandpaper, before you paint. I've always
used Krylon paint and had good results. A couple of coats usually does the
trick just fine.

All the best,
Brent
www.weidefamily.net/vanagon/