upgrade predicament

I inherited a 7507 running an old 11.1 release that does not support FEIP2; I need to upgrade the IOS to support a FEIP2 blade but in order to do this I need the ethernet access that I don't have. So I'm in a catch 22 here. Any thoughts on what I should do? I'm not the Cisco expert and I can't seem to find a way to upgrade the IOS over a serial connection from my pc. I'm thinking I may have to setup a T1 connection into the Cisco just to have TFTP access. I hope there is a better way. Thanks for the help...