Ironically, to do this we need a party.  The whole system is geared towards parties, so we need to play the game.  But this would be a party with a difference.  The only policies would relate to the selection and conduct of its candidates.  Selection would be through open primary.  Anyone can stand, anyone can vote.  The selected candidate would then receive the full backing of the party machine. National publicity would be geared towards the principle of independence, not a legislative manifesto.  And if anyone actually defied all the odds and got elected, there would be no party whip, just clear guidelines about what is considered acceptable behaviour for a public representative.

Postscript (03/06/2009)

It turns out that there is such an umbrella organisation for independent candidates, the Jury Team (www.juryteam.org).