Advice For Leicester Square Premieres anyone?

I read that the SATC worldwide premiere is going to be in London on May 12th!

I am sure tickets to the actual film will be impossible to get but I want to be on the red carpet when the stars arrive and do the ''walk'' and hopefully get some autographs.

Has anyone done this before that can give me some advice on how to do it, what time to arrive, etc?

Some years back during my bachelor days, I was on a "B and C" invitation list where they sent out stuff like that so that you could get put on the doorman's list of invitees.  I used it to go to restaurant openings, club openings, and some cinema events.

I stopped subscribing a long time ago, but I was always under the impression that it was not terribly difficult to get on one.