Originally made for animezis.org.ua. It seems to work with SMF forums also, but still needs testing. This is my first experience in JS ever. I haven't even learnt it before today. It uses full-text search, marks needed divs with lolz# ids. After that is searches for img tags inside those divs and marks them with roflz#. I don't think this is the best way but it is the only way I could imagine in two hours. I doubt what pattern to use for @include, so I've added *forum*. You can always fix it.

PS: I have no intention to support this script, sorry. But I hope someone experienced will find it useful and will take it over in case it needs to be updated.