You can configure it using xinput.

I tested this in 11.10 and it works very nicely. This selection is from "Ubuntuwiki"

Avoid using Hal for this release because it has known issues. Put the following into terminal, using gedit:

Edit $HOME/bin/trackball.sh using this command:

gedit $HOME/bin/trackball.sh

Then paste this into the file:

#!/bin/bash
dev="Logitech USB Trackball"
we="Evdev Wheel Emulation"
xinput set-int-prop "$dev" "$we Button" 8 8
xinput set-int-prop "$dev" "$we" 8 1

# xinput set-int-prop "$dev" "$we" 8 1
# xinput set-int-prop "$dev" "$we Button" 8 9
# xinput set-int-prop "$dev" "$we X Axis" 8 6 7
# xinput set-int-prop "$dev" "$we Y Axis" 8 4 5
# xinput set-int-prop "$dev" "Drag Lock Buttons" 8 8 

Make sure trackball.sh begins with #!/bin/bash. Make the script executable by running this:

chmod +x $HOME/bin/trackball.sh`

Add the following lines to $HOME/.bashrc, using gedit $HOME/.bashrc and put this in the file even if it is empty:

xmodmap $HOME/.Xmodmap > /dev/null 2>&1
$HOME/bin/trackball.sh

Edit $HOME/.Xmodmap using: gedit $HOME/.Xmodmap

pointer = 1 8 3 4 5 6 7 9

Log out and back in and viola!