In most cases you can convert your old slurry machine to use diamond with minimal aggravation. The main components are making sure a magnet will stick to your wheel head (most of them are iron, so that's not much of a problem), making sure your wheel head is flat and true (somewhat more of a problem - check with your local machinist to get this done), and speeding up the RPM of your machine.
As to working with a pottery wheel, these are normally aluminum so you'll need to "skin" the head with metal flashing in order to have something for the magnetic disks to stick to. Then you'll need to speed up the motor and make sure the wheel head is balanced. Most of these wheels were never meant to run at higher speeds, so the wheel head may not be balanced for running at higher speeds.