[Views + Flag] Changing user's flags in Views Custom Field.

Hello there, I hope you can help.

I'm creating a shift system where users flag nodes as 'attending' to sign up for shifts. I really need a way for admin users to run down the list of shift attendees, created with Views, and to flag specific users if they have actually attended shifts.

Is this possible at all using Views Custom Field? In particular, I'd love a way to create a custom field with a flag link for each of the attendees so the admin user can simply sign the person in.

I've hunted high and low on the Drupal website and can't find any completed solutions or anything that works. I've tried using the flag API described here: http://api.lullabot.com/flag to add some custom php code but I've had no luck at all.

Thanks for your time.