The former Bohemians and Derry City boss has praised the appointment of the duo and is eagerly anticipating their tenure in charge of the Boys in Green
Fenlon, who recently parted his post as manager of Scottish Premiership side Hibernian, hailed the appointment of O'Neill and Keane as "brilliant" and believes that they will "want to do well" in their first games against Latvia and Poland.
"It's some acquisition to get both," Fenlon told the Irish Times. "If you got one of them you'd be delighted, but to get the two of them is brilliant."
He added: "I'd love to have 10 minutes with them in the dressing room to see how it works.
"I don't think it will be a problem. The two of them are professionals and are good people and they want to do well."
Meanwhile, Latvia manager Marian Pahars has conceded that his side face a "difficult" task against the Boys in Green when they face off at the Aviva Stadium.
"Of course I know all about the changes in Irish football, and maybe we have come at a bit of a difficult time – I mean for us," the former Southampton striker told reporters ahead of the clash.
"The players will be excited, they want to show themselves to the new management, the staff, they want to prove themselves and get their places.
"Maybe somebody wants to get back in, someone to secure, so it will be difficult. But it doesn't make a big difference, we still have to go and play football and not be afraid to do that."
Republic of Ireland take on Latvia at the Aviva Stadium on Friday November 15 before travelling to Poznan to face Poland four days later.