probally just flip the bike and if you have to find something small and thin to slide into the for from the bottom if there is a hole there. Other wise flip upside down and see if it will slide out.
Then to reinstall, just thread it back onto the bottom of the bolt and slide it in and snug it up. Should be easy to fix.
I was thinking of doing this exact thing. My concern is that the bolt has flipped inside the steerer and I may damage the carbon if I tighten it facing the wrong direction. I could see that bothe sides are not the same with a flashlight. I think I am just going to take it to the local bike shop and have them remove it and put in a new one.Goto home depot and get a really long bolt that matches the size of the stemcap screw. Thread it onto the compression plug no a little and pull it out.