Sitting in his bedroom at 11 years old, watching the music video for Aerosmith’s “Dream On,” the idea of being part of such a band was a faraway dream for Jon MacLennan. But, 16 years later, that same young guitarist has gotten more than he asked for, not only playing with the iconic Steven Tyler, but also with Julian Lennon, John Lennon’s son.

MacLennan, a UCLA alumnus, plays his 12-string Rickenbacker electric guitar alongside Steven Tyler on Julian Lennon’s new single, “Someday,” set to be released via iTunes today. The three recorded the track at the famed NightBird Recording Studios in West Hollywood for Lennon’s upcoming album, “Everything Changes.” MacLennan’s collaboration with the two artists comes on the heels of his third studio album, “Songs from Box Canyon,” released on March 28.

While at UCLA, MacLennan was an ethnomusicology student with a concentration in jazz studies, where he studied a variety of disciplines, including studying under the tutelage of Wolf Marshall, a lecturer of jazz improvisation and guitar master courses.

“Jon’s success arose because (he has) a very receptive mind and (is) able to look at all types of music, not just his own discipline,” Marshall said. “He was able to digest all of that material and make it work within his own mosaic of what his style was going to be.”

Marshall said that this interpretive ability allowed MacLennan to play John Coltrane’s “Giant Steps,” one of the most complex jazz tunes in the catalog, for his senior recital, which is not an easy task for an undergraduate jazz student.

MacLennan said he remembers vividly the sensation of receiving the opportunity to work even indirectly with his childhood idols like The Beatles.

“Just to even be able to get close to playing with them is a chance not too many people get,” MacLennan said. “When you get that call, your heart is pounding, you know. The adrenaline is rushing. This is why I’ve been sitting in my room practicing for 10 years.”

For MacLennan, playing with Lennon wasn’t as nerve-wracking as he thought at first. In fact, Lennon was a very down-to-earth kind of guy.

“The great thing about (Lennon) is that the spirit of John lives on through him,” MacLennan said. “With the song we made, ‘Someday,’ the lyrics are very much like those that John made. Someday, the world will find peace.”

MacLennan said he has always wanted to play music, picking up instruments since he was 2 years old and catering everything toward music, a passion that his parents have always supported.

“He was always making it happen,” Diane MacLennan said. “His first job was at Baskin Robbins 31 Flavors and he would sit outside and play guitar for people while they were eating. If there wasn’t a show, he would make the show.”

Before ever making appearances in studios with the likes of Julian Lennon or Steven Tyler, MacLennan had already played in bands for years, getting his first studio gig when he was 16. Subsequently, MacLennan played on soundtracks for Twentieth Century Fox and Disney Channel, and by the time he graduated from UCLA, had already released two full-length albums, “Dreams” and “Suspicious Love.”

MacLennan said his experience at UCLA, exposing him to a multitude of musical forms, was crucial to his culmination in working with Lennon and Tyler. Receiving such an education allowed MacLennan to adapt to Lennon’s alternative musical style.

“What’s interesting about Julian is that he’s very world-based,” MacLennan said. “I was playing a 12-string guitar. And he wanted me to play it like a sitar, which I was able to do.”

In addition to his work with Lennon, MacLennan has also released his third studio album, “Songs from Box Canyon.” The album was inspired by folk music as well as his first living situation after leaving UCLA.

“I was living in this rustic house where half of the wall was just stone from the side of the mountain,” MacLennan said. “It was a story that I wanted to tell my grandkids. I lived in this house where you had to chop wood for the wood-burning stove and I wrote an album there.”

MacLennan has had great success thus far in his career working with such musicians as Lennon and Tyler but it hasn’t made him slow down at all, he said. If anything, it has only driven him to work harder.

“That’s a great opportunity, to be able to be in contact with people like that,” Marshall said. “But here’s the thing, if you’re not prepared for that opportunity then you’ll look foolish. You can get in the door, but you have to be able to stay in the room.”