Is this possible?

If there's a long slot in the back or front, you can add those plastic sleeves that you can buy most anywhere. They have the one piece of plastic that you slide in the slot, then it has those plastic CC/picture holders attached.
 
I did it to mine, bought the filofax inserts and use it both as an agenda and a wallet. I love it! I get lots of complements as well from my Pomme Agenda.