Adding a Form 1098-E to taxes already filed and sent.

Hello, I have what I think should be a simple problem to solve. My father has a student loan that he took out in his name; I make the payments on it. According to the law, I see that he's eligible to take the deduction on it since it's in his name. He has already filed his taxes for the year. Is there a straightforward way to amend his return so that he would get the money for this deduction back from the IRS? It looks like it would be the 1040X form? But I'm not sure what portion of it needs filled out, what to write, etc. He doesn't want to be bothered with it, but I'm trying to do the legwork for him so he can just fill out a small bit of the paperwork and reap the benefit. Any help would be appreciated.