These tables can usually be converted fairly easily because you usually have the servo system already in place, but it depends on what make of optical trace system was on there, some of the really old ones like the older Linde tables with westinghouse trace system, you would need to replace the motors and drives. You will find a few companies listed in the CNC zone, Torchmate being one company that offers kits, but If you have a large table, I would recommend going with servo's as opposed to steppers.
Al
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.