Cones: Umm..the only ones that come to mind are made by a company called Black Diamond Racing. Basically, look up "isolation devices" at an online hi-fi shop. They're kinda like spikes you see under components. I'm sure some Outlaws around here can recommend some of the isolation tricks they use.

Damping material contraption: There are such things as bass diffusors but those don't really stop bass from spreading. They are used to get rid of extra bass or to stop standing waves (basically low frequencies that get multiplied in certain shaped rooms).
I do know that a company named Auralex makes a pad called the "Gramma." It can be used to isolate subwoofers. Here's a link:
http://www.auralex.com/sound_isolation_gramma/sound_isolation_gramma.asp

Hope all this helps!