You need to lay threads down and configure it to connect to that database. Run any altertables needed in order to upgrade the database.
IC you are saying is there a way to backup just posts as you have not shut off your board yet.
Well the simplest way is the one done above. A whole backup takes mere minutes if that to install via commandline. You run the altertables and your done.
I would work on configuring you new software the way you want it. Then when all is running good shut down your current board and restore the database and run the proper altertables. You will be good to go.
