Brandon Wilson recently managed to get Linky (http://brandonw.net/svn/calcstuff/Linky/) to the point that you can emulate a USB flash drive using the TI-89 Titanium and a raw image of sectors you supply.
He packaged the program, the image for the NT Offline Password and Registry Editor boot disc, and the PC program to create TI-89 Titanium Flash applications out of raw sector images at: http://brandonw.net/calcstuff/NTPasswd.zip.
YouTube video showing it:
This same thing could be used to boot DOS or Windows 3.1 as well -- anything known to fit on a floppy disk (or bigger -- there's about 2.3MB to work with).
Hopefully this also gets people more excited about the prospect of a real USB library coming to the TI-89 Titanium, so that it can enjoy all the usb8x goodness that the 84+/SE has.