Well ultimately I'd be splitting that into two unrelated requirements, mounting http, and mounting an iso. Obviously the iso one is very standard using mount -o loop, but the http part, i'd turn to FUSE for as a first port of call. TBH, I'm not sure how well maintained this HTTPFS example is, but by a spooky coincidence, their example usage, actually includes mounting an ISO...
http://httpfs.sourceforge.net/