You should be able to take off the decorative trim on the pocket using a combination of tapping-in/pulling-out the finish nails and using a trim bar. Once you get it off, you have the working room that's about 3-1/2" wide which is the standard width of a 2x4. Your power drill may fit in there so you can unscrew the tracking or you may have to do it by hand (or with a cordless screwdriver). And when you get your new tracking, there are a couple of kinds of tracking. One kind allows the door to come off the tracking w/o having to remove trim and the tracking in the wall, and there's tracking that ALLOWS you to remove the door from the tracking w/o all this demolition. Search around Home Centers, Door & Window stores (see Yellow Pages), and the WEB.
When you get the door and/or tracking, be sure to let the retailer know that you're replacing an existing pocket door, and you're not doing a 'new' installation.