OK, I believe that the whole project can't really be done easily. Jens is planning for quite some time a new A600 board and he's done a GREAT deal of work in CAD. Maybe he'll manage to produce it ! (I hope!)
Working in a Coldfire project by yourself will need a great deal of inventment for producing these boards.
I hope that I'm wrong and everything will be smooth in creating this accelerator for any of A500 or A600 miggys.
Good luck anyway