I can sell you one if you'd like. I'm not sure what sort of drive system you've got on your Techno, but even if there's no separate 4th axis driver, you can probably borrow the Y-axis (which generally stays in one position during 4th-axis milling) to run it. Just make sure to lock the Y-axis physically in place while you're doing this, since the motor won't be holding it. Try to provide the same kind of motor used on the Y-axis to run the rotary table.
Another thing you might consider is to excavate a trough for the 4th axis assembly in your table. Putting the axis on the table plane instead of above it would double the diameter of workpiece you could deal with.]