I dont know about a program, but I guarantee its possible. I use Acid 2.0, which is pretty fucking old and I can do it.
You need a cable for your iPod that plugs into your headphone jack. Then you plug the other end into your computer. I forget what kind of cable its called, but it basically makes the output from your iPod input to the computer.
Then I'd just play the song on the iPod, run Acid, and record while its playing.
I know that's a pretty unprofessional way to do it. You're recording in real time, and the sound quality is bound to be worse. But if that's what your goal is, that's one way to do it.