Is it possible to change email login for iTunes account?

Use the MyInfo tool mentioned in this article
http://www.apple.com/support/itunes/store/email/

The account name cannot be changed.
The email address used for that account does not have to be the address used fort he account name.

If you started an account with the name Joe@here.com and your email address is Joe@here.com, then later get new email address of Joe@soemwhere else.com, your account name will still be Joe@here.com.
You can change the email address associated with this account but the account name will still be the same and will still work, even if you no longer have that email address.

It defaults to your email but before you save it the very first time, you can change it.