It is not an easy task to remove the shift knob. I did it after I got the shift lever assembly out of the car.
You can gain access to the shift lever assembly by pulling the top portion of the center console out. First, remove the rubber tray from the small bin at the bottom of the front console. Next you will need to remove the screw that is on the back side of the plastic peice that goes around the bin. Now open the storage bin in the center between the seats. The top and sides of the center console are two separate peices. Gently and carefully pull up on the back of the top peice of the console that goes from the front of the storage bin to the front of the center console. Once you remove that peice, you can see how the the leather boot is heald in, the frame around it just snaps into place, so carefully pull the frame out of the mounts. Now you can lift the leather boot up to see the shift lever, and the "zip-strap" that holds the leather boot in place. You can also see where the lever bolts to a peice that comes up from the transmission with 2 10mm bolts. You can now get the shift lever assembly unbolted and removed, (you will not be able to get the leather boot off either end of the lever until you remove the knob.) I am told that a tool designed to remove and replace the new style of in-line fuel filters will spread the bottom of the knob open wide enough to slip it back up the shaft and over the wide flare that flares out against the knob to create pressure which holds the knob in place. The knob is also glued on the shaft. It took some time and care, but I was able to force the knob off the shaft with a screwdriver.-I know,-not the prefered method, but I was careful and managed to do it without causing major damage.
The stock lever is smooth on the top end, and made of hardened steel, thus you will not be able to put threads on it easily. The stock shaft is also mounted in rubber,which is in a peice that bolt up to the part that goes into the trans. to do the actual shifting in the trans.. It seems that this is done to reduce noise, etc.. With the solid lever I do hear some noise vibrating up the shaft from the trans., but only at slow speeds, without the stereo on, and without my foot on the floor
It doesn't bother me. I also really love the way the new handle feels, both in my hand, and when I use it to shift. I can't wait to get my new shifter and try it with this handle!
If you are wanting to replace the knob with a threaded type of knob, you will have to fabricate a threaded lever, (shaft,) that will bolt up in place of the stock one. I'm sure the system they use for the stock knob is great for easy manufacturing, as they just throw some glue on it and jam it on the shaft, but it doesn't make it easy if you want to replace it.
I know this ended up being a long post, but I hope you could follow the directions if you wanted to. I hope this also gives you an idea what you would be getting into if you wanted to try it.
Best Wishes and Good Luck!