Expanding Spray Foam that's works on EPS foam.

[TallDude]

Here's a Spray Foam that dries at a 1 lbs foam density, that is compatible with EPS foam. The Dow "EnerFoam' single can with a built-in replaceable plastic tube nozzle. This could be helpful for small repairs. 

[PonoBill]

I've never had a problem melting EPS with two-part foam, other than mixing too much and getting sticky crap everywhere, but that looks handy.

We use two part foam in racing cars to fit drivers to a seat. You make a doubled contractors trash bag, tape it to the roll hoop and the bottom of the seat back, mix up the foam and dump it in the bag, sit down and tighten the seat belts. The smart guys do it in small, careful increments. I've had it come up out of the bag and get in my hair. Patience is a virtue--someday I've got to get some of that.