1. Boot to live CD
2. Use bitcoin to generate your wallet.dat and however many keys you want.
3. Extract the public AND private keys (well, when they finally merge the PULL request on github)
3a. on a separate sd card, store all your public keys so you can get to them later
4. PRINT the keys out on your printer, and leave some extra space and use a pen to copy them down again (printer ink can fade over years)
5. Put the keys in a security envelope, and then in a tamper-evident manila envelope.
6. Go get a 2"x5" safety deposit box at your local bank for $10/yr and put the envelope in there.
6a. (optional) include a small sd card with the wallet.dat and plaintext keys so it's easier than importing keys manually
7. Don't forget to pay the annual lease for the SD box (perhaps pay several years in advance?)