The sort of events necessary to do this easily haven't been implemented yet. It's required by the AI stuff, though, and a few other things.
Trying to implement a heart beat event yourself will be problematic, I think. The only thread safe way to do it (in the public release) would be to queue up a simulation SimCommand that requeues itself over and over... I think. I don't know if the GameSimulation object is exposed to scripts or not. Looks like from the player context getSystems().getSimulation() might do it.
I'm a little fuzzy on the old scripting.
But a Timer won't really be good because you'll potentially be doing things that aren't thread safe.
Okay, thanks for the tips. I was looking around for a class that would queue itself, and be ran each loop