I really don't know if it would even be possible. One thing I can recommend is if you do anything it will have to be with the "record from power on" option, because the other way uses savestate info which is completely unportable between versions of fba due to changes in the cpu & sound core structures. The "record from power on" option basically records just the input info and a little header data. Though, it is dynhuffman compressed input data.
Good luck,
- dink