I see you did not get many replies, I have the same problem on my Centaur.
Did you manage to find out how to do it. I put in a question regarding a stiff rudder and now that the boat is coming out need to remove the rudder to inspect the bushes. Not sure what I will be looking for, suspect I will have to pay a professional.
I have a different set up (Westerly Seahawk) But I am sure they will be similarly put together. I sepnt ages tryingto get the rudder off then I found a woodruf key in the bit I could not see. Pulled that out and the rudder fell off I have undone all the obvous bolts first though. I am sure it will be easier than you imagine..
Best of luck.
If its the same as the Berwick: after removing the tiller assembly and while supporting the rudder remove the collar from the rudder stock just above the cockpit sole then lower the rudder into the hole you've previously dug. You'll probably have to drive the bolt through the collar out with a brass drift, in which case have an assistant hold a heavy object behind the stock to absorb the shock, or improvise a means of pressing it out. With a Pageant you will be able, with a few friends and a crate of beer, to tip it forward to avoid the digging.