In the film, Will Smith's Agent J travels back in time to 1969 to meet his sidekick Jones' character Agent K, as a younger man.
Brolin plays the younger Jones in the film, and in a bid to nail the movie veteran's physical and vocal ticks, the 44 year old surrounded himself with a collection of Tommy Lee movies and sound editing equipment for 12 weeks, insisting the movie's success hinged on his portrayal.
He tells the New York Daily News, "I went down to Mexico and got a small motel room and just spent time with my computer, (the sounding editing programme) GarageBand and watching all his movies. Syllable by syllable, I just kind of built up (the interpretation). I'd get confident about one syllable and was stoked for the rest of the day - and then I'd go have a drink."
And when it came time to show off his hard work on set, Brolin, who was forced to undergo an hour of make-up to look like a young Jones, made director Barry Sonnenfeld cry in awe.
Brolin adds, "I was very confused at first. I wasn't sure where it was coming from. But he was just very happy."
And Smith is hoping viewers appreciate all that Brolin did to make the movie work.
He says, "Josh, he's probably not going to get credit for that performance. But it's very powerful and difficult and he risked his whole career. You mess up Agent K? That would not be funny."