Contrain movement along x axis

Hey guys, im trying to edit the character motor so my character can only move on the X axis.

im creating a side scroller and i want to use the original charactermotor and platform controller scripts but for the life of me i cannot work out how to edit the script in such a way that it stops movement one way but not the other. does anyone have any ideas or suggestions?

what should i be looking for? has anyone rebuilt the script for a side scroller?

I have used added a rigid body and tried to use that but when my character motor script was active it would make my player jump and rotate upwards with no control. Any ideas, and suggestions would be greatly appreciated.

Dave