old serial mouse DB9 for Desktop

Solaris 10 on an Ultra 45, there are two serial ports (A and B) And I need to be able to use an old serial trackball mouse in the dt enviornment. Do I have any options? Where do I configure the X server desktop environment (if possible?) to use an old serial pointer device instead of it's current configuration of using the USB mouse?
Thank you so much!

I been lookin at the OWconfig file in /usr/openwin/server/etc and tryed adding an entry to point to /dev/ttya (com port A) under the mouse section, but that didnt seem to work. It woulda been a stroke of luck.
I hate to think it is impossible to do. There are two COM ports, I have a good working serial mouse, theres gotta be a way! Maybe not tho? Most will say to just buy a USB pointing device...but this is not an option for us.