Fred:
...
> As I said in an earlier post there is an article on using a (different) 
> Sun mouse on Linux.  The protocol used was msc.  From looking at the 
> output with an oscilloscope that protocol does appear close if not correct.
 Type-4 and -5 mice seems to been made by mouse systems:
https://www.oldmouse.com/mouse/mousesystems/sun.shtml
http://www.telltronics.org/hardware/SunMouse.html
My own sun moues is a type compact-1 and is done by Logitech.
So your primary choises would be msc and mman (in gpm parlance).
> As I said in an earlier post I haven't been able to get gpm to do 
> anything with the pointer.
Have you tried:
 mouse-test [ device ]
Regards,
/Karl Hammar