Increase mouse pointer speed in System Shock Portable
Solution 1:
In DOSBox, the mouse sensitivity can be altered by changing the setting "sensitivity" in section [sdl] in the file "Dosbox.conf".
The default value is 100 and can be changed up to 1000.
I don't know if this is helpful for you in this situation but it might be worth a try.
http://www.dosbox.com/wiki/Dosbox.conf