N910h modem and n910c Roms

I have a n910h and I want to flash a n910c rom. So here is the question. If I do that and additionally If I flash a n910h modem, does that work for me?

Or the second part how can I extract out the modem part from a n910c rom, only for me of course. Is there a "how to do" guide that you can direct me to read and find out ?

Thank you in advance..