The Govan-born star will share the secrets of the trade with youngsters at the weekly classes at the Pearce Institute.
It is part of a National Theatre of Scotland project, The Tin Forest, which is being run as part of the Commonwealth Games Culture 2014 programme.
People from four city previously industrialised communities are being invited to share their memories of the past and dreams for the future to create a series of large scale public performances.
Iain, who started acting at a free weekly class when he was 11-years-old, has returned to Govan to take part in the project.
He will be joined by other tutors, including acclaimed director Lu Kemp, actors Stephanie McGregor, Frances Thorburn, Ros Sydney and Gavin John Wright as well as casting director Lenny Mullan who worked on Neds and The Magdalene Sisters.
Iain, 32, said he hoped the project would leave a lasting legacy in Govan.
He said: "I hope it encourages people to not continue to look past this area.
"Govan is still somewhat deprived and this might show people not to write it off and not to write off the wonderful young people coming out of this area."
Iain first attended free acting classes at Whitefield Road Community Centre before securing a place at London's Sylvia Young Theatre School.
Looking back, he is convinced he would not have gone into acting had he not had access to free classes during his youth.
Iain said: "When I was a boy in Govan whatever you were interested in, there was a group for it. There were groups everywhere that were free.
"I was one of five, my parents wouldn't have been able to afford my acting if they had to pay."
The new classes will offer acting, voice, communication skills and focus on building young people's confidence.
They will run on Wednesday evenings until July. No experience is required.
Anyone interested should visit the Pearce Institute at 8pm on Wednesdays.