I am trying to adjust the speed of my trackball mouse, I have searched all over google, and several forums, the only thing I can find is to use the xset command. There are a lot of postings showing the general command to get the information, then they all say something like "to set speed
mouse The m option controls the mouse parameters; it may be
abbreviated to ’m’. The parameters for the mouse are
‘acceleration’ and ‘threshold’. The acceleration can be
specified as an integer, or as a simple fraction. The mouse,
or whatever pointer the machine is connected to, will go
‘acceleration’ times as fast when it travels more than
‘threshold’ pixels in a short time. This way, the mouse can be
used for precise alignment when it is moved slowly, yet it can
be set to travel across the screen in a flick of the wrist when
desired. One or both parameters for the m option can be
omitted, but if only one is given, it will be interpreted as
the acceleration. If no parameters or the flag ’default’ is
used, the system defaults will be set.

If the ‘threshold’ parameter is provided and 0, the
‘acceleration’ parameter will be used in the exponent of a more
natural and continous formula, giving precise control for slow
motion but big reach for fast motion, and a progresive
transition for motions in between. Recommended ‘acceleration’
value in this case is 3/2 to 2, but not limited to that range.


and "
$ xset m 3/2 0
"

However no matter how closely I try to follow these instructions, I either get an error msg "command not found", or nothing at all happens, except
what I just typed disappears and I'm back to the $ prompt.
Also the instructions say to put the new xset values into a xinput(?) file, or edit the .xorfg(?) file, with no instructions on how to do either of
these.
I am at a total loss here, and I really need to adjust the sensitivity of my device. I have some medical problems which cause my hands to shake and
this thing is so sensitive that it is hard to do any delicate operation, such as clicking on small boxes, resizing windows and such. A regular mouse
hurts my hand and arm, so I need the trackball because it is comfortable, but if I can't get this solved, I may have to go back to a mouse.

Sorry for the long post but I wanted to get as much information as possible.