I don't know how it works because I've never seen one (of that type) in person; but it looks like the type fixture once advertised or described for sharpening router bits, right on the base of a router. A small cup wheel was inserted in the router collet, and the router bit in the fixture. Beyond that, you'll have to play detective. Or maybe someone will chime in that has used one or seen the instructions.
I do have one of the type that was used to sharpen helical cutters for a door planer (that used a router motor sidways as the power source). Never used that one either since I have a T & C grinder.
smt