There is an alternative method without hacking all surfaces.
You must modify the template of the thing that you want it to affect the surfaces.
In this method I don't think you can get the specified wall reference, but if that is not neccesary for you, it may do fine.
In the template of a thing, make its type "weapon" (If you give the parent template as "_weapon", it does it), give its type flag, so it gets exploded on every surfaces out there.
Then on the exploding template(make the parent template as "_explosion"), attach a cog(which you also need to add thingflag 0x400), and let the new cog to do something.
That way when it explodes(you don't need to give any effects on the exploding template, if you don't want anything visiual on hitting surfaces), the explosion gets created calling its cog to do something.
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