Currently it is not possible. It is not that simple either as when you originate a call from fop2, you do it via the asterisk manager, not the device itself, and the manager does not know the specific config you might have in your device/setup.
You could use originatechannel and set it to dial a Local/xxx entry, that you can send to some custom dialplan of your writing that can set the callerid based on whatever logic or configuration you have. That might work, but I am not totally sure.
Best regards,
