How to get music from someone else's itunes library onto your ipod?

My brother has an iTunes library on his computer. I never download music from my computer because I go on iTunes on my ipod touch and buy all the music from there. But how do I get his music onto my ipod touch? Thanks for the help!How to get music from someone else's itunes library onto your ipod?
You can set your iTunes to "Manually manage music and video". And then one iPod can sync with up to 5 computers.How to get music from someone else's itunes library onto your ipod?
just manually sync your ipod check the box that says Manually sync songs