"We started getting the ones like the girl talking about mining for oil and crystals and gold. Every so often you would be, 'Perfect - this is going to be great'.
"But I wasn't sure it was going to work until we were halfway through recording. I didn't really know."
McKenzie said despite his worries, the recording session - featuring a vocal tag-team of local pop, rock and hip-hop stars - was memorable.
"It was great. It was particularly hilarious watching both Savage and Dave Dobbyn sing about bubbles."
McKenzie is soon to be seen in local big-screen black comedy Two Little Boys, which he shot on a break from writing his Oscar-winning song for The Muppets.
From a script based on a book by Duncan Sarkies - who penned some Flight of the Conchords episodes - and directed by Sarkies' co-writer and brother Robert, the film stars McKenzie as "Nige", a man who accidentally kills a Scandinavian back-packer and turns to his mate Deano for help.
"I read the script in a Harley Davidson themed hotel in Milwaukee when I was on tour with Conchords. I was laughing out loud. I had read a bunch of really bad Hollywood rom-com type films and a bunch of Hollywood comedies that I was going to audition for.
"But it was just such a contrast to read something I genuinely found funny, that I was just really into being involved."
Two Little Boys opens at local cinemas on September 20.
Check out the extended video for Feel Inside (And Stuff Like That):
-TimeOut