Is there an entity for "any"

[DRedshot]

I don't think the wildcard '*' is supported in SetEntityPlayerInteractCallback, so unfortunately you might have to do it the long way.
Try doing this: SetEntityPlayerInteractCallback( * , "MonsterAttack", true);
I don't have a clue whether it will work, if it doesn't, try suffixing all entities in that room with a number, and calling a for-loop like so:

for(int i=1;i<=10;i++){SetEntityPlayerInteractCallback("entity_"+i , "MonsterAttack" , true);}

(Doing it this way would require renaming every object in that room to "entity_1" "entity_2" and so on, Instead, you might want to set an interact callback in the level editor, by typing "MonsterAttack" (without quotes) in the PlayerInteractCallback box, which can be found by clicking an object, and clicking the tab at the top right)