Just to close the loop on this thread...
I checked into it and in order to make it legit you have to be a company (DBA filing) and also be approved by the Collegiate Licensing Company (CLC). They serve as a clearinghouse for collegiate licensing. You have to have the company that will actually print the shirts approved by the CLC as well. In addition to that, you have to purchase the "officially licensed" hologram stickers and hang tags from another company. On every article sold royalties are paid to the university.
As you can imagine there are fees associated with every step of this process. Honestly, if you wanted to set up a company and start printing a variety of USF items, it's not all that cost prohibitive, but for a one off like this (that may not even be approved) it is.