They will pore over the damning Royal Commission report and try to find a safe way back underground.
Stevenson said he has no interest in reopening the mine - only in recovering the bodies.
He said it was a "serious situation", with high volumes of potentially explosive methane gas in the mine.
"This is not a decision we'll take lightly," Stevenson said.
One option would be to pump nitrogen into the mine to neutralise the methane to safer levels, Mr Stevenson said.
He said re-entry to mines has been done in the UK many times, but none of them were operating under such "appalling" standards as Pike River, he said.
He said the tragedy has damaged New Zealand's reputation "quite severely" in the UK mining community.
Stevenson also criticised the system of recognising hazards but failing to do anything about them.
If they came up with a sound plan, it would need to be implemented by trained and experienced mine personnel, the consultants said.
Dr Creedy said: "It has to be a safe process."
He said everyone has to be on board with the plan: "The fighting and the blame has to stop."
Local publican, Bernie Monk, spokesman for most of the 29 families, said the families were aware of the dangers, and would be relying on the three experts.
"If these guys say it can't be done, than we must accept that," he said.
Monk, whose son Michael died in the November 2010 disaster, says he will be pushing Prime Minister John Key to fund a recovery operation if a feasible plan is possible.
"We need our men back," he said.
"We don't have any great expectations.
The experts have funded their own expenses to help the families, who meet tomorrow night in Greymouth and will be kept updated with the experts' fact-finding mission.
Dr Creedy was impressed by the Royal Commission report.
He said its findings "read like a horror story", especially the inspectorate's failure to pick up on the problems at the mine.
"I've never seen anything as serious as this."