Good thanx, but I'm still not sure what the leds_asus_touchpad device is exactly. Maybe it's not the main device but some sort of ghost helper device.
It may be better to keep trying to configure the ImPS/2. If you do try that again you could check "synclient -l" and
xinput list-props 'ImPS/2 Logitech Wheel Mouse'
and make sure the touchpadoff=0 and the xinput deviceenabled=1
synclient touchpadoff=0
xinput set-int-prop 'ImPS/2 Logitech Wheel Mouse' 'Device Enabled' 8 1
and if those don't work then try modprobe using the verbose option so you can see what's happening:
sudo modprobe -v psmouse
and if you could lshal the device while it was loaded by hal you could see if hal was doing its job.