If someone still looks after a solution: I used
Code:
synclient
to set following properties on my ASUS X55a (with Ubuntu 12.04):

Code:
synclient RightButtonAreaLeft=1650
synclient RightButtonAreaRight=3320
synclient RightButtonAreaTop=1600
synclient RightButtonAreaBottom=2300
this properties define an area (by coordinates), which register a right click event. Perhaps you have to figure out yourself, which coordinates work best for your device.