Sydney's Daily Telegraph reported that Cheika is assisting Roosters coach Trent Robinson - a longtime friend - by working with the Sydney club's coaches and the players' attacking skills.
"He is helping push myself and the assistant coaches to improve and challenging our ideas and helping push us again in 2020," Robinson said.
Cheika quit the Wallabies after five years in charge following their Rugby World Cup quarterfinal defeat in 2019.
He has been linked to French rugby union club Montpellier, but is with the Roosters one day a week, at least through the end of pre-season.
Cheika - a fan of the Roosters' arch rivals, South Sydney - told the Daily Telegraph:" I've loved it. I was really honoured that they thought I could contribute. I want to make sure the stuff I'm doing is contributing the way Trent wants me to."
Current Kiwis stars Jared Waerea-Hargreaves and Joey Manu are part of the Roosters squad now exposed to Cheika's coaching methods.
Robinson said: "Cheiks loves the footy environment," Robinson told the paper. "He is a rugby union coach but he grew up in the Eastern Suburbs and he just loves footy, whether it's union or league."
The Roosters- winners of the last two NRL titles - and Wallabies had a joint training session in 2014, thanks to Cheika and Robinson's friendship.
Cheika coached Irish club Leinster to a European Champions Cup title and led the Waratahs to their first and only Super Rugby crown in 2014 before taking the Wallabies job.
He led Australia to a 2015 Rugby World Cup final defeat to the All Blacks, but overall had a disappointing overall record with 34 wins, 32 losses and two draws from 68 matches.
Other rugby union coaches have had league links. Eddie Jones brought Canberra Raiders coach Ricky Stuart in to observe England's Rugby World Cup training in Japan and he has recently added Melbourne Storm assistant-coach and former Australian international Adam Ryles to his coaching staff.
Former All Blacks coach Steve Hansen had a rapport with legendary Australian NRL coach Wayne Bennett.
Ireland coach Andy Farrell was a former Great Britain rugby league international as was Shaun Edwards, Warren Gatland's longtime defence coach with Wales, who is now in the same role with France.