I found the
Press Release about this offer.
Only thing not already mentioned here is "... each WIND F2G subscriber can “enroll” only once in 2010" though whether that's once per SIM or once per person (if the SIM is registered to a person) I don't know. Probably of no significance.
I looked for registration forms to download so I could fill them in ready to register my F2G SIM against my passport, but couldn't find any on the website. (There are some on the Vodafone website - but they're Vodafone-specific.)