William Houston went to the beds of two boys, then aged 11 or 12, and sexually abused them during the night while he was working as a dormitory supervisor at St Augustine's during the 1960s.

Houston told one of the boys "you know we should not be doing this".

He led the other boy away from his own bed and abused him after the child had been crying and feeling sick.

The 82-year-old man faced Victoria's County Court on Wednesday, where he was sentenced to a total of seven years in prison.

Judge Gerard Mullaly said Houston had not only committed a "heinous crime" but also demonstrated "utter hypocrisy" by giving out the impression he adhered to the morals of a religious order dedicated to protecting children.

He added Houston had exploited his access to and authority over the vulnerable pre-teens.

"You had an outward appearance of adhering to decent morals while acting in private as a man with no morals," Judge Mullaly said.

"Your breach of that trust by putting your perverse sexual gratification ahead of their need to be cared for renders this offending particularly grave."

One of the victims, who cannot be named, earlier told the court he had tried to take his own life in the 1990s after facing decades of trauma.

"I feel robbed of my innocence and my ability to lead a normal, happy and healthy life," he said.

"My future may well have been different if not for that abuse."

The man, now 65, said he felt frightened and alone after the incident.

"I started to feel shame and embarrassment, as though it was my fault," he said.

The other man, now 68, said speaking about the abuse was "no easy task" and it took him a "lifetime" to come forward.

"This trauma cost me my childhood, a marriage, and my health. I carry a lot of anger with me ... and feel a lot of shame," he said.

"I was taken from a safe place and put into an unsafe place."

He said being finally heard in court would help his recovery.

In a judge-alone trial, Houston was found guilty of three abuse charges against one of the boys between 1964 and 1968.

He was also convicted of a single charge against the other boy in 1968.

The two men came forward in 2017 and 2018 after coming to terms with how the offending had affected their lives and those of their families.

Houston has been behind bars since 2016 when he was convicted of abusing three other boys at St Augustine's.

Judge Mullaly ordered that Houston, a registered serious sex offender for life, must now serve a total sentence of 15 years and six months in prison.

He will be eligible for parole after 10 years and nine months.

Australian Associated Press