I had the same problem. I run Backtrack 4 in a Parallels VM on an early 2010 macbook. After installing Parallels tools, there are some lines added to xorg.conf as well as some lines already there
I commented out /dev/mouse and enabled /dev/psaux.
# The mouse device. The device is normally set to /dev/mouse,
# which is usually a symbolic link to the real device.
# Option "Device" "/dev/mouse"
Option "Device" "/dev/psaux"
# Option "Device" "/dev/ttyS0"
# Option "Device" "/dev/ttyS1"
Next, in the same file:
Since parallels is looking for /dev/mouse, but this did not exist on my system, I just made a link that pointed to psaux, thusly:
# Parallels Mouse section
Identifier "Parallels Mouse"
Option "Device" "/dev/mouse"
Option "Protocol" "auto"
$ ln /dev/psaux /dev/mouse
The above two actions may be redundant, but whatever it works now. I got this info from post #7 in this thread:
macbook pro hd install (multiple os) - Remote Exploit Forums
I copied the key portion here:
I did this module stuff he mentions here as well, which maybe you should do first and then reload modules (depmod -a). SOrry things are a little out of order. I'm kind of just writing this as I go, and my kid has a fever and it's late yawn
By default, the generic X mouse driver (mouse) is used. This won’t let you use cool features like two-finger scrolling, two/three-finger taps (right/triple click respectively), etc. So, you need to use the synaptics driver, but this isn’t trivial to do. The appletouch kernel module needs to be loaded before the usbhid module, otherwise the usbhid mode will act as the driver for the trackpad (it is USB after all). To do this, I blacklist both drivers, and load them manually in the order I want. (Please do let me know if there is a better way of ordering the modules):
# appletouch should load before usbhid so it claims the trackpad