Holmes will make a cameo as an arrogant amateur actor who joins staff from the medical centre to put on a performance of Oscar Wilde's classic The Importance of Being Earnest.
Holmes' character, Leslie Grant, is playing Lady Bracknell, creating a story-within-a-story situation that Holmes says was "quite hard to get my head around".
But he loved the experience, despite having to learn a sizeable chunk of dialogue from the play and spend a stinking hot summer's day in a stifling Edwardian frock.
He's not a big Shortland Street watcher, but when the soap's producer approached him he jumped at the chance to play an actor playing Lady Bracknell.
And the prospect of wearing a dress didn't bother Holmes one bit: "It's a costume.
"I didn't mind that at all."
Shortland Street producer Steven Zanoski said Holmes, who did a bit of acting when he was younger, was the "consummate professional" on set.
"Beyond the novelty of Holmes in a dress, this is a fantastic performance from a very talented actor," Zanoski said.
Zanoski says when the Importance of Being Earnest storyline came up, "it got us speculating as to who was the biggest New Zealand celebrity that we could put into an Edwardian frock".
"Paul was my immediate thought for Lady Bracknell, despite everyone doubting we could get him."
But get him they did.
"God knows what people will think, but I did my best," Holmes says.
• Holmes' cameo on the TV2 show will screen in early April.
