How can you make a custom xbox live gamer picture?

I want to know if I can make on if my Facebook pictures a game picture on xbox live. Well u guess ant picture for that matter. How can I do this?How can you make a custom xbox live gamer picture?The only way to use your own picture would be to mod it. Using a program on your computer. The only problem is that you can get suspended for modding and Microsoft could even ban you.