You cannot use scripts on a static wall, therefore you can break it. The walls compatible with script are located in entities>special (these are the mansions base and castle/worn cell base walls)
The script you are looking for is SetPropHealth. If you look this up on the following page, you can set the Health value of your wall to zero:
http://wiki.frictionalgames.com/hpl2/amn..._functions
To set up the script for it in the level editor, you need to creator a script area that is the size of the wall, cover the wall with it, and then click the "Area" tab, and check the box that says "Item Interaction", and add a "AddUseItemCallback" for your script.
For the full effect, use particle systems and sounds in a timer. If you have any further questions, or if I didn't explain it well enough, feel free to ask for further assistance.
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