Level Indicator table cell

Ok im trying to write an app that uses one column of table to display a list of all the disks connected to the computer, and the other column has level indicator cels to dispaly how much space has been used, so how would you address the indicator cell in the table ? Ive been trying for a while, but no luck. Any help would be great.

Looks like it might not have access by Applescript just yet. Cocoa works though.