I am having this problem too. I'm using LMDE on a usb stick for the moment (I'd like to know that the problem can be resolved before installing).
xinput gives me (amongst other things)
↳ PS/2 Elantech Touchpad id=12 [slave pointer (2)]
so I'm guessing my asus x451 has an elantech touchpad.
The above link for pimping up the touchpad has, in the Configurations chapter,
"First of all, mark the following functions in the Touchpad section of the “Mouse and Touchpad” settings: " ... which is a little difficult as our problem is that there *is* no touchpad section of the Mouse settings.
When I use the same usb stick on another laptop, the trackpad tab is there, and works a treat! On *that* machine (an old toshiba something-or-other) xinput gives me
↳ SynPS/2 Synaptics Touch Pad id=11 [slave pointer (2)]
So I'm pretty much convinced it's just a driver that needs to be installed ... but as a noob user, I'm not really sure how to find it.
In any case, I'm already having less troubles with lmde than the windows 8 that was pre-installed on my computer.