Certain systems offer a track ball style of mouse referred to as a ZMouse. This enables you to control the movement of the mouse pointer from the Z rail.
The last line of the parameter file (DOWNLOAD) should read:
N1000 ZMOUSE2
or
N500 ZMOUSE2
To enable the ZMouse, verify that the last line of the DOWNLOAD file reflects the above statement. Modify the line, if necessary.