Poppa...I bought some high adhesive hook and loop (velcro) from McMaster Carr
http://www.mcmaster.com/#hook-and-loop-fasteners/=pn2bi9.
I then attached the hook side to the horizontal metal firewall in the passenger compartment. I used 2" hook & loop so I would have room to change the position of the bag if I wanted it lower or higher (sorry about the poor iphone quality pics...too lazy to break out the SLR):
I then cut the loop section and affixed it to the bracket:
Position the backet where you'd like on the firewall and you're set:
Once you're sure about the position you like and you've lived with it a few days, you can drill two holes in the firewall and permanently bolt it in. I bought some chrome (completely unnecessary) buttonhead allen bolts with a 1/2 inch spacer to move the bag forward a touch - but I will probably remove the spacer as the bag works better for a passenger closer to the firewall. I bought some neoprene washers to insert between any metal to metal contact to cut down on rattling.
However, I suspect the velcro will work just fine as a permanent solution as well, with the added benefit of not permanently modifying the car One day you may want to ditch the bag, in which case you'll just have a hell of a time removing the industrial adhesive from the firewall!
I also affixed the front vanity plate with
3M automotive trim tape it's amazingly strong stuff, but we'll see how it does with the heat
