How do I fix a pocket door wheel track?
Regarding your question on tools to remove the track, this article (Natural Handyman - How To Repair and Adjust Pocket Doors) says:


  Many pocket doors can be adjusted with
  special tools from around the top of
  the pocket frame with the door in a
  partially closed position. These tools
  are often specially angled wrenches
  designed to fit into that little gap.
  These tools are part of the assembly
  kit supplied with the pocket door, but
  are rarely given to homeowners by the
  builders. Without these proprietary
  tools, you have to improvise with or
  modify standard tools.


If you can't get to the warped part of the track with any tool that you have (or can find), then you will need to cut a hole in the wall for access.

This article (Ask the Builder - Fixing a Pocket Door) has a great description of how to get access to the track.  The article talks about replacing the track but it also gives a warning that if the new track is not the exact same dimensions then the little project will become much bigger.  So you will have to make a decision to cut the wall to get access to the screws to replace the track or just to get to the warped section of the track. 

A quote from the article:


  Remove the door from the pocket and
  take it off the track. Use a
  flashlight and peer up into the pocket
  cavity. There is a good chance you
  will see the screws that fasten the
  track to the frame. It is now time to
  cut an access hole on one side of the
  pocket wall. This hole will allow you
  to get your hand or arm into the
  pocket so that you can loosen and
  remove the screws and subsequently the
  track.