There is currently no way to pause an FSM.
One way to go about doing that is to have a global event go to a state with nothing in it, but you'll have to figure out how to return and such. Basically just a per-object way to pause everything.
That seems like it would be really hard to maintain, though.. Changing the timescale of the whole scene works great, but if you want some object to be ignoring the pause then thats an issue.