Ive also just baught a Richbrook Gearknob, Lift reverse one...
Looks Awesome, but i dont even know where to begin with the other one, where do i cut ?? or Rip ??
You need a hacksaw and a bag to catch all the plastic sh*t that flies off it.
Before you do anything, take off the gear nob gear direction cap that is on the top of the gear nob (you know, the bit that says 1-2-3-4-5-R), that is simple .. you can just take it off with your fingers.
Now the fun..
Saw it vertically untill you are right down to the white plastic skelton.
You will need to stop and keep checking to see how far down you have gone - that is important! Once you have got down to that stop sawing and use a flat end screwdriver to make it a bit loose.. It's not over yet. The plastic skin is quite tough, so you will need to keep sawing it - I would suggest you saw it horizontally now, again stop when you see it is down to the plastic skeleton.
Every now and then keep trying to make it looser with the screw driver. Now saw the other side of the gearnob vertically and repeat the process above.
By this point the plastic cover should be in peices or just fall off in your hand which will expose the ivory white 'skeleton' under it.
I hope you have muscles...
Repeat the process above with the saw, but obv you dont need to cut anything else off, other then this white skeleton. This is a very hard plastic and not easy to get off, you will need to go at it quite alot! I would recommend you cut the white bit in lots of places, and keep attacking it with the flat ended screw driver.. Then after about a good 40 mins sawing, it should be in peices and all you should have left it just a round metal shaft.
Warnings:
*DO NOT cut the metal gear shaft!
*DO NOT attempt to cut the reverse gear lever on the metal shaft (the bit you pull up with your fingers when going into reverse)
Jobs a good'un.. Now stick your new nob on