A Jesuit priest and human rights lawyer has accused Tim Minchin of endangering the integrity of the royal commission into sexual abuse after the comedian penned a song describing George Pell as "scum" and inviting the Cardinal to "come home and frickin' sue [me]".

Father Frank Brennan has warned that turning the commission into a "laughing stock" runs the risk of derailing proceedings.

"I don't think it's altogether helped by having songs about a key witness, calling him scum, and a buffoon, and a coward and that sort of thing before the commission does its task," Father Brennan told ABC's the Drum program.

"Because if we turn it into a laughing stock, then the big losers ... will be the victims themselves."

But some survivors have already expressed anger at the royal commission for allowing the Cardinal to give evidence from Rome, rather than returning to Australia.

Minchin is donating the proceeds of the song, called Come Home (Cardinal Pell) to a GoFundMe page set up to send 15 representatives, including survivors, to Rome to witness Pell's testimony in person.

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The crowdfunding campaign surpassed its initial target of $55,000, reaching almost $170,000 by this morning.

The video of Minchin performing the song, which includes such lines as "Go home Cardinal Pell, I've got a nice spot in hell, with your name on it, so I suggest you toughen up and go", has had almost 400,000 views on YouTube.

The song peaked at number one on the Australian iTunes songs chart earlier on Wednesday.

'Bless him and his hipster fans': Laurie

Comedian and presenter Meshel Laurie, who set up the GoFundMe page, said the release of Minchin's song was not coordinated with the fundraiser.

"I know he [Minchin] has been passionate about this issue for a long time," Laurie told ABC's Radio National.

"I spoke to Tim this morning for the first time in years, so we didn't coordinate it, but I think he maybe heard about it or read about it on social and decided he wanted to jump on quickly."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 6 minutes 55 seconds 6 m Australian comedians supercharge an online campaign to help abuse survivors confront Cardinal George

Laurie said she had no idea the songs proceeds would go to the campaign until Tuesday night.

"It's incredibly generous of him," she said.

"He's got us lots of extra attention, lots of extra dollars.

"Bless him and his hipster fans."

Laurie said any extra funds raised would be donated wisely.

"The extra money as always, as noted on the GoFundMe page, will go to mental health services in Ballarat for survivors of sexual abuse by clergy," she said.

Former New South Wales Labor premier and Catholic Kristina Keneally said she laughed when she first heard the song, but on second listening was brought to tears.

"It spoke really deeply to the abject failure of the Catholic Church to deal with the child sexual abuse crisis," Ms Keneally said.

"I have yet to see from the Vatican the type of frank, honest, acknowledgement of the damage that it has done and the recognition of the things that need to change in the Catholic Church to ensure this never happens again."

Cardinal Pell, 74, will appear via video link from Rome after the Royal Commission into Institutional Responses to Child Sexual Abuse accepted a doctor's report that said he would risk heart failure if he flew to Australia to testify.

The royal commission must give its approval for those travelling to Rome to watch the evidence in person, abuse survivor Stephen Woods said.

In a statement released by the Truth Justice and Healing Council, the Catholic Church said it was important Cardinal Pell give his evidence in "the most effective and timely way possible".

"So that this case study can be finalised, that the commission can make findings and that abuse survivors can, hopefully, move forward with their lives," the statement said.