OK. Here's another go at posting these instructions. I got 'em from popgun who got them from someone else whose partner kindly translated them. I'm happy to acknowledge that person if I can find their username. I've tried to tidy the translation up a tiny little bit. I'm also happy to edit the post if people can point out ways to improve it.
Instructions for Honda One-Key System
This product uses the key of the vehicle so that, by combining three types of tumblers, you can make a key cylinder that fits.
1. Combine the three types of tumbler to make the key cylinder that fits your key.
Tumbler A, B, C
2. Use 5 Tumblers( A) to fit into the cylinder after the spring.
3. Hold tumbler and key cylinder on top and insert the key to find out if any tumbler comes out high or low.
4. Pull the key out from the cylinder, holding these cylinders from the top. (Note: presumably this means the cylinders that are high or low in the previous step.)
5. Exchange Tumblers that came out when you insert your key to Tumblers B. (keep the springs inside)
6. Repeat this step (A to B to C) until no tumbler comes out when you insert key. (Hold on top so that you push tumblers to pop out and disassemble.)
7. Insert the key cylinder into the inner cylinder as shown in the Figure below and confirm that the inner cylinder turns smoothly.
8. Pull out the key cylinder from the inner cylinder. Hold lightly from the top tumbler, pull out the key. Install the Stopper Spring (black) and stopper tumbler as shown in the Figure.
9. Insert the key, as shown in the Figure. Then, pressing lightly on the tumbler and inserting the key, confirm that the stopper tumbler pops.
10. Apply the grease in the position shown in the Figure, with a thin coating on the tumbler’s inner cylinder. Please do not use grease other than the supplied grease.
11. Attach the Stop Tumbler while rotating the inner cylinder along the slide. Guide the stopper tumbler.
If the inner cylinder does not turn on, please double-check to see whether something other than the stopper tumbler not jumping out is happening.
12. Push while turning to the right.
13. Pull out the key to make sure inner cylinder does not comes out.
Disclaimer: I've no idea whether these are right. Consult an expert before following them!