There are many mis-understandings, here's some clarifications on Shimano freehub-spacing:
Code:
speeds stack-width cog-thickness spacer-thickness c-t-c spacing
7-spd 31.9mm 1.85mm 3.15mm 5.0mm
8-spd 35.4mm 1.8mm 3.0mm 4.8mm
9-spd 36.5mm 1.78mm 2.56mm 4.34mm
10-spd 37.2mm 1.6mm 2.35mm 3.95mm
Notice that not a single cog or spacer will interchange between the different speeds. The cogs are all different thickness as is the spacers and c-t-c spacing between the cog-centres. The difference between 7 & 8-spd is the smallest and sometimes you can mess with cable-tension to get most shifts to work OK if you mix & match 7 & 8-spd parts. If you adjust RD so that it shifts well in the middle of the cluster, you only have the end-gears that may mis-behave.
As to adding a cog to 8-spd to get 9-spd, there are many ways to do it. The only way to re-use the existing cluster with 100% compatibility is to grind down the spacers to 2.54mm so that you have 4.34mm c-t-c spacing (including the top cog with built-in spacer). Note that you can't just replace the 8-spd spacers with 9-spd ones as the cogs themselves are thinner on the 9-spd cluster.
The 11t cog represents a unique configuration. It requires a Hyperglide-C freehub body where the splines do not go to the very end:
http://sheldonbrown.com/images/2k7-bodies.gif
.
that's because the 11t cog has a solid outer-surface for the necessary strength and this cog won't slip down all the way on a regular freehub body. You will also need a 11t-specific lockring, the regular lockring will cause the chain to ride up on the lockring instead of falling down into the sprocket teeth.
Then the issue of RD comes in. If the one on the Alan is an 8-spd Dura-Ace, it will not work with 9-spd Dura-Ace shifters. Shimano got rid of the unique Dura-Ace cable-pull distances when they went to 9-spd and made Dura-Ace the same as the rest of the line. You may need to get 9-spd compatible RD.