This depends on what exactly you want to do.
If you want to have an enemy do a few attacks in a row, it's simple enough-- have a skill that calls a Common Event. Have the Common Event use Force Action (Immediate) Attack a few times in a row. It'll work fine.
If, however, you want the enemy to have several complete actions in one turn, there's only two ways that I know of-- a custom script, which you'd need to ask for in Script Requests, or Unka Josh's Cheating method.
For this second method, it's simple.
Put two (or more) enemies in the troop, but put them exactly on top of each other. They'll look like one enemy, but with double the actions. (It will be two different enemies to fight, of course, which may not be what you want.)