I actually had mine off yesterday. It wasn't hard at all. Took 3 seconds. Pull and twist back and forth until it releases.

There is an indent machined into on the gearshift shaft, and something spring loaded in the shift knob latches into it. You'll hear it click into place when you put it back on.

 

The gearshift lever is attached pretty solidly. It has a rubber isolator, which helps dampen vibes between the shift lever and tranny -- but also makes it feel like you might break something when you pull off the shift knob. I had it all apart to work on my inner shift boot. The whole assembly is pretty stout.