I have removed the steering wheel a number of times (replaced with a genuine Startech unit, see pics in my gallery) and I can confirm that the steering shaft splines are extremely fine. There's a notch for a centering tooth in the splines, BUT it's a female tooth so it doesn't guide you into any specific position (leave it to a female to be vague).
Also, the clockspring/steering angle sensor can rotate a bit, and if you're not bang-on with the alignment it can throw you off a bit.
To remove the airbag: extend the steering column out as far as it will travel. Due to tight clearances, you will have to turn the wheel to fit a T-Handle behind the wheel (there are two small bolts, one on either side of the wheel). With the car still on, turn the wheel 90° to the left, and remove the LH bolt using a T30 (torx) T-handle. This might require a grunt or two, the bolts are rather tight. At this point, simply LOOSEN them (don't fully remove them). Turn the steering wheel 180° to the right (the 3:00 position of the wheel should now be at the 6:00 position). Loosen the RH bolt using the same method above. Return the steering wheel to center, and shut the car off.
Now, unplug the battery and wait ten minutes before further poking about. This will allow the capacitor to release its charge, preventing the airbag from knocking your teeth out. After ten minutes, you can use an Allen wrench that is close to the T30 to easily back the bolts out of the airbag. The airbag, once loosened, should simply wiggle out of the hole. Use a plastic trim tool to gently pry the airbag wire out of the back of the airbag (it snaps in, but the connector is a 90° version and is a pain in the **** to remove with fingers). Now, you can go about removing the center bolt. A breaker bar will do the trick. If you have someone on-hand to hold the wheel, all the better.
Safest bet: once you've removed the center nut from the steering wheel (the one that holds it on),
mark the splines with a grease pen BEFORE removing the wheel from the splines. When you slide the wheel back on the splines, the wheel should be able to match the exact position prior to removal. And remember, be careful of the angle sensor.
To reinstall the wheel, reverse the order above. I added a dab of Blue Loctite to the center nut for security.
Do not reconnect the battery until you've plugged the airbag back in, and you've snugged the two set screws with the Allen wrench. Once you've done that, you can reconnect the battery and crank the car to turn the wheel -- then use the T-handle to torque the bolts down.
Cheers!!
