sorry, i'm not using a mouse with my PPC.
but i wanted to know why you want to use a mouse..?!
you can play the games (especially the older lucasarts-games like monkey island 1 & 2, DoTT and so on) even better with a touchscreen than with a mouse IMO
I got a Stowaway BT mouse, and it works fine on my XDA mini running Pocket PC 2003SE. However, SDL doesn't support it correctly in landscape mode, and the cursor isn't drawn correctly, since the driver draws over the top.