Can i add songs from one computer on my ipod and also from another computer?

i had to exchange my ipod touch... home button wouldnt work... but i dont have internet so i went to someones house to use their labtop which i registered my ipod and i like some of their songs and i cant get them is their any way i can get all these songs on my ipod touch and get the ones i have at home but not delete them if so please help and also how do i put my email adress like wen i want to get apps and stuff how do i add mine and take off someones elses