Captain O'Connell has made "rapid improvements" in his bid to beat the chest infection that ruled him out of Sunday's RBS 6 Nations victory over Scotland, team manager Michael Kearney confirmed.
O'Connell watched training on Tuesday and spoke in an analysis session, with Ireland bosses remaining confident the 34-year-old will train fully on Thursday.
Forwards coach Plumtree said O'Connell's potential return would prove a huge boost ahead of Saturday's clash with Wales in Dublin.
"I've been around a long time, and Paul's right up there in terms of the professional rugby players I've been involved with," said Plumtree.
"I've coached in New Zealand and South Africa at the top level, and they can't talk highly enough about that guy.
"He's huge in terms of how he applies himself to his own preparation, making sure he ticks his own boxes so that he can lead the team right, and that takes time and effort.
"He's really fussy about how he goes about his business.
"I've been involved with a lot of really good leaders that don't do that a nd he is one guy that I've just been really impressed with.
"The players have got such great respect for him, and that's what makes him such a good leader.
"He doesn't do all the bantering and yelling off the pitch, he gets on with it, he's a smart operator: he knows the right questions to ask and what buttons to press, and he's a good man.
"It would be great to have Paul back for this big contest, so that's why we're looking after him."
Cian Healy is expected to shrug off an ankle knock in time to face Wales, scrummaging in training on Tuesday but not running.
Rob Kearney should also recover from his bruised calf.
Longer-term casualties Eoin Reddan, Luke Fitzgerald, Tommy Bowe and Donnacha Ryan will not return to Ireland training this week.
Michael Kearney believes the quartet have a chance of returning to provincial action in the next fortnight.
Ireland's team manager admitted pinpointing recovery from infection is no exact science, but predicted O'Connell beating his illness in time to face Wales.
"I think the nature of any chest infection it is a little bit of wait-and-see, it doesn't just clear up overnight, but he's on his third day of treatment," said Kearney.
"But again, all the signs are he will be fit and ready to go, so we're very confident he'll be okay.
"He is getting treatment, recovering well and has made fairly rapid improvements from Saturday night."
Wales centurion Gethin Jenkins will replace Paul James at loosehead this weekend.
Wales came under frequent scrum censure in their victory over Italy in Cardiff on Saturday, with James penalised regularly in his battle with Martin Castrogiovanni.
Adam Jones boasts a fearsome reputation as one of Europe's frontline tightheads, but Ireland coach Plumtree is unfazed by the challenge.
"I think our scrum has been really good," said Ireland's Kiwi coach.
"Mike Ross is a good tighthead prop, Cian Healy is a world-class loosehead, and Rory Best is an outstanding hooker.
"That front row is experienced and the big thing is you need to know how to adjust to the opposition and what they are trying to do to you.
"Since the autumn we have conceded hardly any penalties or free-kicks from the scrum.
"We want to paint the right pictures to the referee, and certainly we're pleased with our discipline record so far."
- Sports & Recreation
- Michael Kearney
- chest infection