Ms Tarrant said she was having a great time in Los Angeles - and sang a few lines from another of her son's Muppet ditties, Life's a Happy Song, to prove it - as the town prepared for the US film industry's biggest night.
But there had been some strange moments, with McKenzie being recognised by a tour-bus operator as the family were out driving.
"They just pulled up at the lights and said, 'On our left is Oscar nominee Bret McKenzie'," Ms Tarrant said.
"Bret is constantly recognised, so it's quite surreal. [It's] all go, and the town is glammed up ..."
In Wellington, McKenzie's father, Peter, and brothers Jonathan and Justin are planning to go to the Roxy Cinema to watch the Academy Awards broadcast.
Weta Digital supporters will also be at the party, because their Rise of the Planet of the Apes work is up for the Best Visual Effects Oscar.
Peter McKenzie said hopefully there would be a few cocktails around to celebrate double success for the "Weta boys" and his son.
Despite Bret already having won a Grammy award with his Flight of the Conchords partner Jemaine Clement, his father expected there still to be "butterflies and anxiety" as the hours ticked down to the award.
He said he was proud that his son had carved out a unique path.
"He's always loved music. His grandmother gave him a set of drums at an early age, just to terrorise Deirdre, I think," he joked.
"Our rule of thumb for [all of his sons] was do what you want to do and we'll be here for you.
"He followed his own beat."
McKenzie has a film, Two Little Boys, set for New Zealand release this year and is a member of the Wellington International Ukulele Orchestra.
WHAT TO EXPECT
* It's ninth time lucky for veteran host Billy Crystal with a probable musical parody which will gently mock as many of Hollywood's finest as he can fit into the opening bars.
* The big number for this year's awards is Cirque du Soleil's much-anticipated acrobatic dance show.
* Among the confirmed presenters of awards are Halle Berry, Tom Cruise, Penelope Cruz, Cameron Diaz, Michael Douglas, Tom Hanks, Angelina Jolie, Meryl Streep, Colin Firth, Natalie Portman, Christian Bale and Melissa Leo.
ACCESS ALL AREAS
* nzherald.co.nz/oscars will be live-streaming all the red carpet action from 11am. The official Oscars website also promises a plethora of "backstage all-access webcams" at oscar.go.com/backstage-pass.
ON TWITTER
Official tweets from @TheAcademy (for red carpet & Governors Ball) @OscarGoer (the show itself) and @OscarInterviews (backstage) promise to keep tweeters in the thick of it, while host @BillyCrystal will be tweeting from centre stage.
Other prolific tweeting stars worth following include @EvaLongoria and last year's host, @JamesFrancoTV.
