Running xmonobut (in the original feed, I think) allows you to set the "mouse" using the menu key. It can also be added to the panel and set by clicking the icon. You have to restart X before you can add it to the panel. This seems to undo some of the difficulties mentioned.
I still have a problem with the sensitivity, as similar touches sometimes trigger it and sometimes don't. Also, the fact that a tap moves the pointer doesn't always mean that a click has been registered as well.