You need a PC, Finn's editor and an Action Replay in order to transfer the franchise file from your Xbox to your PC and vice versa.
After playing 2k5 on PS2, I must say that I would have given up football video games after the EA/NFL deal was announced if it wasnt for Finn's editor. I spent $150 on a laptop PC off ebay, $150 on Xbox, $20 on 2k5 and $30 on an Action Replay.
Trust me, it was worth every penny. There's so many things that can be done with Finn's editor that in the end, is truly amazing. Plus, Finn continues to work on it trying to find whatever else that we can use. He recently added the ability to change the NFL's salary cap for franchise files and the ability to change any player's contract in roster and franchise files.
Honestly, the only two things that I wish he could be able to do is give us the ability to edit a Head Coach's name and appearance and the ability to change a team's defensive depth chart. For example, my 49ers run a 3-4 defense but run a 4-3 in-game. Sure, I could use a different team's playbook but like I said, im hoping for the ability to change it in the depth chart setup.