Peter John O'Neill, 61, taught at Burnie High School, Dominic College and St Virgils College before returning to live in New South Wales in the mid-1990s.

He has pleaded guilty to six counts of indecent assault and one count of penetrative sexual abuse of a young person or child which he perpetrated against six boys between 1981 and 1990.

The boys ranged in age from 11 years to 15 years.

Appearing in the Hobart Supreme Court via phone on Wednesday, O'Neill was sentenced to five years' jail wholly suspended.

O'Neill resides in Canberra and cannot be transported to Tasmania because he suffers from a number of medical conditions including morbid obesity, chronic back pain, urinary and fecal incontinence, diabetes and psychotic depression.

He is wheelchair bound and requires the assistance of a full-time carer.

Chief Justice Alan Blow said O'Neill deserved a prison sentence but he was unfit to travel to Tasmania.

He said a wholly suspended sentence was the only option available as O'Neill was unsuitable for community service and had no means to pay a fine.

"There is no legislation which allows anyone in the ACT to take an offender there into custody for the purpose of serving a Tasmanian prison sentence without extradition to Tasmania," Chief Justice Blow said.

"If I were to pronounce [a custodial sentence], it would never be put into effect.

"Because of his immobility, his incontinence, his pain problems and other medical symptoms, his life now is probably more miserable than the lives of most prisoners."

He said O'Neill's solicitors had investigated a number of ways to transport their client to Tasmania, including the possibly of using an air ambulance to fly O'Neill from Canberra to Launceston at a cost of between $20,000 and $45,000, but none were deemed suitable.

Chief Justice Blow said O'Neill had committed dreadful crimes which had a terrible impact on the six victims.

"These crimes all involved grooming, the abuse of trust placed in O'Neill as a teacher and the abuse of trust placed in O'Neill by the boys' parents.

"They all involved predatory behaviour toward vulnerable boys."

Chief Justice Blow said one of the victims had died but four of the five surviving victims had made a victim impact statement to the court.

He said they had spoke of a range of impacts as the result of being abused including continued distrust in others, suicidal ideation, flashbacks, nightmares, anxiety, depression, sleeplessness and homelessness.

He said the boy who had been the subject of the penetrative sexual abuse complaint had attempted suicide twice.

"He has been diagnosed as suffering from post traumatic stress disorder. He has been admitted to psychiatric hospitals more than 50 times," Chief Justice Blow said.

He said when sentencing he had taken into account O'Neill's remorse, cooperation, lack of prior convictions and guilty pleas but not his disabilities because there was no prospect O'Neill would ever be required to serve his sentence.