I can't give you a spot-on advise as I don't use my T61's touchpad but you could have a look here
if not already done.
EDIT. But first do this as root:
cp /usr/share/X11/xorg.conf.d/50.synaptics.conf /etc/X11/xorg.conf.d
After determining the appropriate settings you will write it in /etc/X11/xorg.conf.d/50.synaptics.conf. Read the comments in that file first.