One of the requirements of the UEFA Pro licence course is that students spend time observing other teams and the week-long stint with the All Blacks, brought about by Herbert's ties with Graham Henry, was too good an offer for Keane to turn down.
With the former Ireland captain maintaining a watching brief at training sessions and refusing media interviews, it was left to All Blacks supremo Henry to reveal how Keane has fitted in.
"I'm not quite sure that Roy has got a foot in both camps or not! I think Roy has been great really, he's great to talk to, he's bubbly," Henry admitted.
"Richie (McCaw) had lunch with him earlier. I don't think they chatted about leadership - I think they chatted about experiences, and Roy has got a few of those.
"I think it's good to have a guy of his esteem in the group, that he can share some experiences with the group. Everybody knows him and respects him for what he has done.
"It's great that he chose, along with Ricki Herbert, to be here with the All Blacks for a week as part of their requirement for their final coaching certificate in football.
"They had to spend a week with an international sporting team. It's great that he has chosen the All Blacks."
Keane knows his rugby, he has attended a number of Munster and Ireland matches, as well as internationals at the Millennium Stadium in Cardiff.
The former Manchester United midfielder has also left his mark on the likes of Paul O'Connell and Donncha O'Callaghan, who have name-checked him in interviews.
Even this week, O'Callaghan spoke about the effect which Keane has had on Irish sport in general.
"Roy Keane has brought a huge mentality in back home where Irish people shouldn't just be happy with competing, we should look to win," the second row said.
"You get the perception that everyone thinks we are nice people and we do our best. But he has brought in a mentality of why shouldn't we win and play to win.
"I think it's no longer acceptable to go out and be happy to be thereabouts, you have to go out to compete and win."
New Zealand captain Richie McCaw was delighted to meet up with the revered Corkman, who has even been invited to give a motivational speech to the All Blacks before this weekend's Test.
"Roy said: 'I guess that playing for Manchester United is a bit like playing for the All Blacks'," McCaw explained.
"There is a lot of pride that goes with it and he didn't probably realise until the last six months when he went and played for someone else - it just wasn't the same.
"He realised then what it meant to play and I think our guys find that when they give up or move on, they actually realise what it is all about, the great fun it is playing for the All Blacks and stuff like that so I guess there are a few similarities."
McCaw, who captained the Crusaders to the Super 14 title last weekend, added that it had been a special meeting and one that he would always treasure.