Foam safe CA glue would work(don't use regular CA glue; it will eat your foam!). when gluing foam together, I find plain old white craft glue works well. in a pinch wood glue works; essentially the same as craft glue, but doesn't dry clear. I've heard of people using spay adhesives as well.
Edit... oh I just looked up battlefoam... thats an open cell foam isn't it? hrm... not sure in this case.