The starting flyhalf against the touring British and Irish Lions last year, O’Connor was cut loose from the Wallabies mid-season after a string of off-field problems, prompting the 44-test utility to head to Europe to continue his playing career.
Australian media have speculated the 23-year-old is set to sign a deal with Super Rugby team Queensland in a bid to break back into the national side.
McKenzie welcomed the prospect of having O’Connor available for next year’s World Cup in England.
“The more the merrier as far as I’m concerned,” McKenzie said in comments published in The Australian on Wednesday.
“He has got X-factor. He can make things happen in attack. He is a very tidy player. He can do all the fundamentals of the game and he is a very good goal-kicker.
“He is a pretty complete player and very experienced. He’s got 40-something tests at his young age. If he keeps the same rate of progress he will easily go over the 100 mark. That’s the challenge. He has to resurrect all that.”
O’Connor had his national contract torn up before last year’s season-ending tour of Europe after he was escorted out of Perth airport by police following a confrontation with airline staff.
Months before, he was photographed with Wallabies team mate Kurtley Beale at a fast food restaurant at four in the morning a few days before a match against the Lions.
Local media later reported that he had also missed a team bus and been late for training during the series, enraging senior team mates.
McKenzie said he had kept the lines of communication open with O’Connor, who signed a one-year deal with Toulon, the French giants said in February.
“We have kept in touch. I caught up with him on the (Wallabies) tour last year,” McKenzie said.
“I’m not closing the door on him at all. He wasn’t giving us what we needed. He has gone away and is trying to right his wrongs and change his life a bit.
“The conversations I’ve had he has certainly expressed interest in coming back. It is not going to surprise me if he comes back, but it is up to him to organise it.”
Australian Rugby Union (ARU) boss Bill Pulver last week also said O’Connor would be welcomed back to the fold but would not be given any extra money by the ARU if reinstated.
The ARU usually gives nationally-contracted players a “top-up” on their annual salary paid by domestic clubs which can range from a token amount to several hundred thousand dollars.
(Writing by Ian Ransom; Editing by Sudipto Ganguly)