Sounds like walking around the world to cross the street.
If they have Mac & FCP why not leave it at that? All this extra is going to be more time, more money, likely lower quality. I can’t see any professional having a reason to do that.
If they’re really familiar with Pinnacle (and whatever version they have as there are various with different features) then they should be able to tell you what optimal uncompressed codec they can use. Having to compress is going to be a quality hit and if they force that workflow I’d get them to sign off in advance on accepting whatever it looks like.
You could use MPEGStreamClip to make something with an AVI extension (if that’s what they need) but NONE of this helps you unless they tell you what codecs they can handle.
I’m not sure if you read my other posts so I’m a bit frustrated but HAVE THEM TEST CALIBRATED SOFTWARE as I said before.