You should have instructions that were included with the knob itself. Failing that, here is what I did for my First Strike knob on the SRT-10 (different than a Gen I/II):
1. Remove the aluminum bezel from around the shift boot using the proper allen wrench. Note the position of the bezel and boot, as it has to go on in the EXACT same position or it will not go back on. Looks simple enough, but if you notice there are two pegs on the bottom (different sizes) that dictate the direction of the bezel. Also note that the shift boot will probably turn a little bit as you pull it up, so make sure to realign those holes as well to fit the proper pegs, etc.
2. Pull up the shift boot so that you can clearly see the shaft of the stick shift. You will see that the stock knob is held on by screwing it down on the threaded shaft against a "counter-nut". The stock knob has flat sides on the botton so that you can get a wrench on it.
3. Get two wrenches and place one on the nut and the other on the stock shift knob. Turn each the opposite direction. I am pretty sure you want to go counter-clockwise with the knob and clockwise with the nut. It should "break loose" fairly easily. Once loose, simply unscrew the stock shift knob off the threaded shaft. Then remove the counter-nut as well, as MGW doesn't use it on their SRT knobs (at least not for the First Strike knob).
4. Screw on your new MGW knob. Screw it down to where you feel it is comfortable. While everybody seems to prefer a short throw, you may not want it TOO low. Once you find the "sweet spot", take the tiny allen wrench (provided) and tighten down the set screw on the back of the knob's shaft. NOTE: You don't want to strip that screw or break your allen wrench, but do tighten it very well. Mine came loose on me twice (which I have found is an anomoly) and I finally turned green, bulked up to 12 times my normal size, and screwed it down TIGHT. Never had a problem since. Although the green tint seems to put some people off.
5. Store the stock knob and counter-nut where you can find them in case you ever sell your car and want to keep the MGW knob (and who doesn't?). Put the boot back down and reinstall the bezel. You will find the bezel still probably turned on you, so be patient and play it like a puzzle. Don't forget that the boot also needs to line up correctly.
One final note: George at MGW e-mailed me after he saw the picture of my installed knob (above). He said that he designed the lower part of the knob (with a set screw instead of flat sides) so that it could rest on top off the boot and look perfect. I didn't know this, so did the ol' Hulk routine and managed to get the boot over the bottom part of the new knob. It was too much work to reverse, so that is how mine sits. I kinda like it.
Good luck with your new shift knob. You will love it!
Chris