If I'm reading this right, the OP has a gun which has the slide in place but which has had its trigger pin pushed out leaving the action in bits inside the frame.
I might suggest that if the slide will go back far enough to allow you to remove the rear cover and the striker assembly, then by firmly pushing down on the barrel at the ejection port, the slide may be freed enough to allow it to be removed. I can't think of any other way to do it. It may also help to pull downward on the trigger itself as the slide is being pushed forward. The process will require a couple of people's hands to accomplish I think.