Okay, first you need to set up your image points. Open the sprite editor:
1. Click the Image Point tool.
2. Click the "+" button next to the point name dropdown and enter a new image point. Give it a name that's easy to remember, like "hitbox."
3. Select the newly created "hitbox" image point in the dropdown and click the sprite where you would like the image point to be set. (You will have to do this step for every frame of your sprite's animation.)
Next we go to the Event sheet and set up your action:
Viola. (It also helps if you don't disable your event group )
Also, when did mediafire become so stupid? It used to be nice and streamlined, with one-click download, and no popups. How the hell are the popups getting past my blocker anyway? Ugh. Everyone should use http://fileshack.us/ , it's much less annoying. </rant>