How do I get power of attorney for my boyfriend if he is in jail?

My boyfriend has asked me to file his taxes for him since he is incarcerated. He was brought into custody the beginning of this year but has all of 2011 to account for. Ive read about him and I signing a power of attorney agreement but HOW do get that and then as his girlfriend HOW do I apply it to his returns. Can I even legally since Im his GF? Is there a form in prison that he can send me that will be notarized and signed and then do I send that in with his tax returns that I'm allowed to sign and send in? I usually file my own taxes so I'm aware of the 2848 but does he need to sign that or is that what he gets in prison?