I would just remove the connector on the board and soder the wires direct. Failing that...I *think* I know the ones you mean. They're molex 1.25mm pitch.
**broken link removed**
At least thats what I found in my mouse when I just took a screwdriver to it
I would check ebay, theres plenty of USB cables there with other connections on them for replacements. Alternatively, if you love your mouse as much as you say you do, buy another one, cheapo USB, that will probably have a similar cable assembly. But yeah, as the others have said, photo's would be nice.
Blueteeth