Comment 75 for bug 124440

This solution works for me:

sudo apt-get install imwheel zenity

Create a bash script and insert this:

#!/bin/bash
# Version 0.1 Tuesday, 07 May 2013
# Comments and complaints http://www.nicknorton.net
# GUI for mouse wheel speed using imwheel in Gnome
# imwheel needs to be installed for this script to work
# sudo apt-get install imwheel
# Pretty much hard wired to only use a mouse with
# left, right and wheel in the middle.
# If you have a mouse with complications or special needs,
# use the command xev to find what your wheel does.
#
### see if imwheel config exists, if not create it ###
if [ ! -f ~/.imwheelrc ]
then

cat >~/.imwheelrc<<EOF
".*"
None, Up, Button4, 1
None, Down, Button5, 1
Control_L, Up, Control_L|Button4
Control_L, Down, Control_L|Button5
Shift_L, Up, Shift_L|Button4
Shift_L, Down, Shift_L|Button5
EOF

fi
##########################################################

CURRENT_VALUE=$(awk -F 'Button4,' '{print $2}' ~/.imwheelrc)

NEW_VALUE=$(zenity --scale --window-icon=info --ok-label=Apply --title="Wheelies" --text "Mouse wheel speed:" --min-value=1 --max-value=100 --value="$CURRENT_VALUE" --step 1)

if [ "$NEW_VALUE" == "" ];
then exit 0
fi

sed -i "s/\($TARGET_KEY *Button4, *\).*/\1$NEW_VALUE/" ~/.imwheelrc # find the string Button4, and write new value.
sed -i "s/\($TARGET_KEY *Button5, *\).*/\1$NEW_VALUE/" ~/.imwheelrc # find the string Button5, and write new value.

cat ~/.imwheelrc
imwheel -kill

# END OF SCRIPT FILE

Now run the script and set you desired mouse wheel speed.

Thanks to: http://www.nicknorton.net/?q=node/10