Agreed with the above. The trackball has two sensors, one vertical, one horizontal, so there's no hardware way to fix the problem. Software...maybe. You'd have to use a clever driver to mux the two inputs together and rotate. It could be done, but you'd need a very clever mouse driver.
Some like that do exist, though I'm not sure they'd be compatible with your trackball. May be worth looking at.
-->VPutz