After being on remand in custody for 14 months, he was granted electronically-monitored bail in March this year to attend the residential treatment programme at Auckland's Grace Foundation.
Five months down the track he had made such good progress he was now mentoring others at the programme.
Wilson told the court the people he helped were a mirror of how he used to be.
"The main thing is their attitudes, how they carry themselves and how they try to project a 'cool guy' image," he said.
He focused on "just reassuring them that it's OK to be vulnerable, just admitting it and holding yourself accountable for what you've done".
It "pissed him off" thinking about the harm he caused the community. He recognised the "snowball effect" of it.
Rehabilitation was about "having the right motivation, to stay on the right track", he said.
Wilson was being sentenced on 74 meth dealing charges, involving 43 grams of the drug and offers to supply it, and for three charges of offering to supply cannabis.
He pleaded guilty after an earlier sentence indication from Tomlinson of a starting point of three years' imprisonment with six months uplift for the cannabis dealing charges, and a further six months uplift to mark that some of the offences were while Wilson was on an earlier sentence.
The meth charges all carried maximum penalties of life imprisonment and the cannabis charges carried 14-year maximums. The judge said he would treat all the charges equally for totality reasons.
In setting the starting point, he accepted Wilson was a "subsistence drug dealer" who controlled the flow of the drug and skimmed off the top of his supply to support his own drug habit.
Determining sentence discounts, the judge gave 20 per cent for Wilson's guilty pleas and credits for the time he spent on remand in custody and on bail at the Grace Foundation.
There was a six-month discount to acknowledge Wilson's progress in rehabilitation. It was also the reason he was willing to convert the notional end sentence of eight months' imprisonment to four months' home detention, to be served at the Grace Foundation.
It was the least restrictive sentence he could impose, Tomlinson said. He wanted to acknowledge Wilson's progress but also needed to address the seriousness of the offending.
"As a judge in this court and in other courts in Northland, I am constantly confronted by the harm that meth is causing in our community - to children, to other family members, and to loved ones," Tomlinson said.
"It's an insidious drug that causes pain and misery wherever it goes. Wilson was part of that - he caused pain, misery and suffering to himself and others."
For whatever reason Wilson went into rehab, it led him to an epiphany that "this stuff [meth] is just no good," the judge said.
That epiphany, Wilson's ability to rehabilitate himself, and the opportunity he was afforded to do that by the Crown not opposing his bail application to go to the rehabilitation facility and his lawyer's work in getting him a bed there, satisfied him a prison sentence was not necessary, Tomlinson said.
