I went to Michaels out here, a arts and craft store and got their silver paint pen. It is actual paint, not an ink marker. Worked fairly well, wish it has a better tip though. You can see some problems on there.
I went with FatMat Extreme, it is Butyl based and not asphault based so it shouldn't melt in the summer. And is a bit thinner then Dynamat Extreme, which is fine for me, I just wanted a little sound deadening and heat protection.
Ryan