Yes, you can. As far as I know, each person has to be booked entirely with points or entirely with cash but the entire cabin doesn't have to be booked entirely on points. Plus, you'll have a $95 transaction fee.
For example: We are booking our cruise partially on points and cash. DH, DS, and I will be booked on points and DD will be booked with cash. I have been told over and over that booking cruises on points is not cost effective, but it works great for me.
You can call member services and they will give you the cash price per person.