Are you talking about product called Kool Patch (made by company called Kool Seal)? Got the idea from that same VW article you refer to:

http://www.type2.com/library/heat/intrir2.html

I used it on my recent restoration, along with the Evercoat Q-pads, and the foil backed insulation.

Excellent stuff in my opinion, first impressions are promising. Mixture of fiberglass, rubber, and asphalt, no smell, and $2.99/ quart. I can't remember how long it took to completely dry, I gave it a couple days. Don't get that stuff on any bolt holes, once it dries it's as hard as a rock!