How can I use the used space on my time machine as an external disk to store a copy of my itunes lib?

I have a macbook pro and a time machine with a huge disk - with lots of empty space. Is there a way I can use the unused space on the time machine to store the overflow of my itunes lib.

Itunes only offers a purchase only option on some things and thus I am forced the keep them .

My Itunes lib has consumed most the space 300 gigs available- about 34gigs free.