You may to look for ASUS Smart Gesture. You can try doing a search for it. If you find it then open it and see what options are available.
Not sure if this will help but may be worth a try:
"The below steps work on all Dell, HP, Acer, Asus and Toshiba laptops as the problem is with the Synaptics touchpad software and is not a Windows related problem.
Simply…
Go to Start > Control Panel > Mouse
Choose the Device Settings tab on the right.
Click the Settings… button
On the left there is a menu. Choose Pinch Zoom. Then UNCHECK the “Enable Pinch Zoom” box.
Click Apply at the bottom and OK to exit and save settings and your Done!"
Source: http://www.lynch.ie/wordpress/index.php/how-to-disable-the-automatic-zoom-on-laptop-touchpad-asus-dell-toshiba/
This video may help:
http://www.youtube.com/watch?v=pAUzJEIXZL0