OK,
I pulled my Flues SBT (early without the crossbolt). It has differences but I think it is the same principle.
From the state of dissassembly that your pic shows you need to:
1 Remove the top lever return spring(cant see if you did in the pic)
2 Remove screw that is in the rectangluar block (surrounds the bolt)
3 Drive out the hammerpin. It is retaining the bolt. You should be able to drive it out so it is just holding the farside hammer and then pull your punch out so it retains the close hammer.
4 Push the bolt out towards the rear of the receiver. If there is resistance you may not have the hammer pin out far enough(or your punch)Remember the hammer pin keeps the bolt from falling out!
5 use a small punch and gently tap from the bottom thru the hole in the spindle, this should loosen the top lever(dont pound on it) Then stick a small screw driver in the hole where the lever return spring was and gently pry the spindle(part with the three studs sticking out)down.
6 Wiggle the top lever around and it should come off of the 3 pins in the spindle and out the back of the receiver. It might come out straight up if there is not a rib extension that the bolt locks into like the "wings" sticking out to the side on my bolt, except it would be one and stick straight out.
If this dosent make sense feel free to ask questions. Like I say the double is probably some what different. Dont force anything!!!
Good luck,.
Ross