So, I can't really control my dissociation. There are times I can fight it a little to keep it from happening, but that usually makes me sick and it's very exhausting. Snapping in and out of euphoric hypomania and PTSD triggered rage is something I've grown very accustomed to when I'm not depressed. Oddly enough, I haven't really started dissociating until this morning during this round. Which is a nice relief, because it's very frightening. I have depersonlized a lot, though but it's usually welcomed when I'm euphoric rather than malicious. The euphoric episodes make me really not care about the depersonalization and not really be afraid of full blown dissociation.
However, when I'm in a mixed episode, that is when I have the most triggers for PTSD. It usually happens when I'm already in that state, rather than a product of a flashback or trigger. I also dissociate a lot more and it tends to get me all screwed up to the point where I don't even know if I'm actually alive or in a dream.

So, long story short followed by digression of topic: I don't know how to control dissociation. Sometimes, I just choose not to fight it by not grounding myself when I feel the onset. I'm not usually a fan of it, either. Everyone's different, though.

I hope you stabilize soon.