Hi, so I ordered these (http://www.ebay.com/itm/261720162556/) off of eBay to put on my HHKB's sliders. You need these ones because they aren't too thick, and they also are a little bit smaller than the diameter of the slider, which allows you to put them on the sliders snugly. I started off by unscrewing the three screws in the back of the board. I don't have a picture for this because they aren't hidden and very obvious.
Once you open it up, it will look like:
(https://farm8.staticflickr.com/7299/16191172310_91f5c4a369_o.jpg)
From here I proceeded to unscrew the 17 screws, and you can't see the 7th because it is hidden behind the controller's wires. I hadn't noticed this one at first, so make sure you get it. After I unscrewed all the screws, the PCB will lift up, but be careful because it will look like this:
(https://farm8.staticflickr.com/7368/16351876986_e893861316_o.jpg)
and you need to make sure when lifting up the rubber cups don't fall off as the springs are underneath and will be hard to line up and they might scatter everywhere. This only happened to 2 of mine, which isn't too bad.
After you put the PCB in the back of the case, you will just the sliders and the top of the board, and will look like this:
(https://farm8.staticflickr.com/7370/16191968517_6f48f77024_o.jpg)
You will have to flip to the front of the board in order to pop them out. I used the back of a small screwdriver, and do not be afraid to push them out as they take a little force. The nice part about doing this though is that if you ever need to pop them out again, it is a lot easier and requires a lot less force.
(https://farm9.staticflickr.com/8663/16191969497_19698f2be3_o.jpg)
You will want to pop them out on something padded, so I used 2 bubble mailers on top of each other. They pierced the top of the envelope , so I used 2 for extra measure. The shift and enter have stabilizers under the plate, so don't push them out too hard, as you will need to unhook the stabs. Here is a picture of them all popped out:
(https://farm8.staticflickr.com/7352/16376131741_eed978d265_o.jpg)
Your plate will now look like this:
(https://farm8.staticflickr.com/7453/15755412184_303cbdb827_o.jpg)
Now you will want to start putting the dental bands on. Try and get them flat at the base of the slider, but if it isn't perfect, don't worry as I checked mine again as I was putting the slider back in the plate. It took me no more than 45 minutes to put them on. It took a couple of minutes at first to find the fastest way of putting them on, but after that it became systematic. Here is the finished sliders:
(https://farm8.staticflickr.com/7417/16191970347_d2c6847108_o.jpg)
Now you are going to reassemble everything, and once again, be careful with the PCB as it is harder to get it in without the rubber cups falling off, and the same 2 fell off for me, but it took me 2 tries to get it in place. You will then put the case all together, and your HHKB will be done with all the dental bands. When you type on it, you will immediately notice the 2 differences; the slightly shorter travel length, and the quietness of the slider upon return. I would suggest this mod to anyone, not because the HHKB is loud already, but it silences it further, and IMO improves the sound and typing experience. Here is a finished video of me typing on it: