I've got enough room to put the ign mod on the outside surface of the firewall, next to the engine standoffs. How do I fasten it to the firewall?

It has 2 screw tabs, but the instructions, (Fuji), and common sense tell me to mount it on foam. Should I put it on a bed of foam and loosely attach the screws? I would think that would make things worse.

Suggestions?

Thanks all!