Thanks for writing to us.
Please try the following steps.
1) Go into c:\program files\DellTPad\
2) In this directory you will see two option
a) DellTouchpad.exe and b) DellTPad.exe
Click on the seecond one When launching this you will see "one finger actions/multi-finger actions", and then it allows you to set single finger vertical/horizontal scrolling.
Make necessary changes as per your requirement.
Let us know if it helped.