Not sure with the EQ6. Most mounts use a dovetail plate which fixes to the mount by a screw that comes in from the side an pushes the dovetail plate against the opposite side of the mount head. The only other type that I know of is used on large mounts where a flat mounting plate get screwed down directly onto the top of the mount head.
I'm not sure if the EQ6 comes with the dovetail plate (if it uses one). If it's not in the box then you will need one. If the tube has an outer diameter of 250mm then you will need 250mm tube rings.
The tube rings should attach to the dovetail plate without to much trouble. Between two and six screws usually.