For your mouse, try the "xset" command. In a terminal, use command:
xset q | grep -A 1 Pointer
you will get a return something like:
Pointer Control:
acceleration: 2/1 threshold: 4
The first value represents the mouse speed, the second is the threshold before the pointer starts accelerating (1 is "off").
Experiment with different values, like:
xset m 7 10
should make it very fast,
xset m 3 10
is about normal
xset m 1/2 1
makes it very slow
To return to defaults:
xset m default
Once you find the numbers that work for you, add the command to ~/.icewm/startup