Removing shift knob...

I bought a 2000 Mustang about a year ago. It already had a silver Type S LED shift knob on it. I've changed shift knobs before, and usually on non-factory knobs, there is an adaptor that fits on the shaft, and then the knob goes over that. The knob is then secured with allen screws, and a cover goes over the bottom to cover the screws. The bottom cover on this knob is very small, and when I removed it, the threads were on the inside of the knob, not on the outside as I have seen before. I have no idea how to remove this knob. Any help would be much appreciated!

Here is a picture of it as well...
http://us.st11.yimg.com/us.st.yimg.com/I/rodi_1919_73862295