Former Wales international Rees took an enforced spell away from rugby from October last year while he underwent treatment at Velindre Hospital in Cardiff.
But after being the all-clear to resume training in February, Rees will now make his highly-anticipated comeback to the delight of McIntosh and the region.
He said: "It's phenomenal news. What can you say about the guy. He's an inspiration to us all.
"I have played with him and he is a fine rugby player. He is also a tremendous friend and person. The boys are inspired by him.
"We have missed him, both off the field and on the pitch. He has come back in and called a spade a spade. He has really intensified training because of his attitude and just given the boys a huge, huge lift.
"They look at him and think about what this guy has gone through. It is unbelievable and we have got no right to complain or be half-hearted in anything we do.
Asked if he expected to see Rees return to action before the end of the season, McIntosh added: "Truthfully, yeah I did expect him to. I have known him a long time and he's absolutely hard and ruthless.
"It's alien to us all what he has gone through. It doesn't happen often. It's not a sprained ankle and it's not a popped collar bone. It's a bad, bad illness that not many people recover from, let alone go on to play rugby at the very highest level. But yes, I did expect to be back because he's a tough old unit and a very motivated person.
"We have lost talismanic men in guys like Sam Warburton and Leigh Halfpenny, who are two icons in what they do. So it's great to have Matthew coming back into the environment, being strong both on and off the pitch."
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