You can use SCEs (single combo events) for stuff like turrets. This usualy involves an event that logically isn't able to generate with a regenerator on it, resulting in weapon fire from weaponse like seekers or bouncers being shot out of mid-air. For a full list of these events check out http://www.geocities.com/atlastsome/jj2/shj2.htm

Also, note that you should NOT use these events in MP levels unless they're treasure or any concept that has to be hosted under treasure, since if someone dies from gunfire from these events in MP they'll get an access violation.