Ipswich meet United on Sunday in what will be a first game in charge for their new manager Ruben Amorim.
It also marks a reunion for McKenna, who worked under Jose Mourinho, Ole Gunnar Solskjaer and Ralf Rangnick ay United.
“I think I've said many times previously that they've all had an impact,” he said. “And it was a great privilege to work with the three of them.
“And, of course, (now Middlesbrough manager) Michael (Carrick) as well, being a really important part of that in his small interim spell, but more probably pertinently as a really close assistant as well over the few years I was there.
“Jose was the one who gave me the opportunity to come into senior football, appreciated my work with the academy side there and saw a talent and a personality that obviously he warmed to, and I'll always be grateful for him for that.
“I really enjoyed the work with him and I think a manager like that, there's no way you can't pick up certain things from his personality and also from his methodology that you will use.
“Ole, I've spoken about before, is someone who I'll hold dearly forever, really. A fantastic person and a fantastic man who did some really good work, but he has human qualities of the highest, highest level in and around football and away from football, and he is someone I hold in really high regard.
“And Ralf was a really good insight for me because it was not that long before I went into a managerial career of my own, so to have the spell with him, seeing him come into a new group of players in a season, and with his methodology heavily influenced from the Red Bull model and his way of working that was pretty clear, to spend time with him and have insight into that model as well on a day-to-day basis was a big, big positive.
“And again, I wouldn't speak about the coaches there without mentioning Michael because he’s someone who I hold in the highest regard and a big influence in my career.
“All great people all have had a good part to play in helping me be the manager that I am.
“But, as I'll always say, you also have to go your own way as you're developing as a coach, not just as a first-team coach, but from the very start you're developing the ways that you want to work and the things that you believe in and what you come to the table with eventually is an amalgamation of all those things.”
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