Finally got around to pulling the rear shocks today. Let's take a walk through the procedure...
First thing to do is remove the shock from the car. Lots of information on this so I didn't document it. If putting on new top hats you should loosen the spring locking rings to relieve the preload on the spring before removing the shock. You can do it afterwards but it's a little bit harder. Once the shock is out you want to turn the damping all the way clockwise. Next is the removal of the adjuster using a 14 mm wrench (it just unscrews):
With that off you can see the reason for turning the adjuster all the way down. There is a rod running through the middle of the shock shaft that needs to be down so that you can use an Allen wrench to hold the shaft from turning while removing the top nut. If you squint you should be able to see the hex machined inside the shaft:
With that off you can disassemble the shock parts:
Notice there is a spacer on top of the top hat that fits into the bore on the top hat, one on the bottom and then another spacer that is machined. This lower spacer serves to locate the dust boot, it fits over a tapered section of the shock shaft. It needed some persuasion with a dead-blow hammer to get it loose off the shaft.
I couldn't find any instructions for using the Feal top hats with Ohlins. GoodWin says you can use them but the various spacers etc make it a little confusing. I ended up using the dust boot locating spacer along with the rubber spring isolator on the bottom of the top hat, and one of the provided washers underneath the lock nut on top. With everything put together I wasn't able to get the correct spring compressed length. For now I went back with the Ohlins provided top hats. I did replace their bumpstops with some cut-down Integra bumpstops as seen in the BBB thread:
Note these are loose on the shaft but that shouldn't be an issue, they will just sit on top of the shock under normal circumstances. When I was messing around with the shocks I found that the spring preload on the right side was higher than the left side. I'm not sure how that happened because I recall checking those measurement several times when setting them up during my initial installation (and the locking rings were tight). In any case they are both even now.