One of the Bali nine ringleaders has married, knowing his execution could be just a day away.

Andrew Chan has wed his Indonesian fiance on the same island his life is scheduled to end within hours.

The ceremony was conducted by a Salvation Army minister and witnessed by close family and friends.

His brother Michael describes the day as tough but happy.

Chan, 31, and Sukumaran, 34, have markedly changed since their Bali Nine plot to smuggle heroin from Indonesia was foiled in 2005.

But pleas to spare the men - Chan now a pastor and Sukumaran a talented artist - continue to fall on deaf ears.

On Monday, an ex-lawyer for the pair detailed sensational bribery claims, alleging judges in their original trial wanted more than $130,000 for a lighter sentence.

Their current lawyers say it's unthinkable for the men to be executed under the cloud of corruption.

They also have a challenge in the constitutional court set for a preliminary hearing next month, but its decision will not be retrospective.

The only man they need to convince, President Joko Widodo, was not receptive on Monday.

"Why not convey it at the time, when it actually happened if ... it truly happened, right?" he said of the bribery claims.

Security has tightened at the port town of Cilacap and the coffins have been prepared for nine prisoners' bodies.

But one of the Australians' lawyers, Michael O'Connell SC, says the momentum can be easily stopped.

"Whilst it's very frightening to see the machinery of execution being out into place, it's worth remembering that stopping this is really just the stroke of a pen away," he told ABC's Lateline program.

Foreign Minister Julie Bishop says she also hasn't finished fighting for the men.

"Indonesia has accomplished what penal systems around the world aspire to do and that is rehabilitate drug offenders," she said in a speech in Sydney on Monday night.

"I'm not asking the Indonesian government to do anything other than it asks other countries in relation to Indonesian citizens."

Sukumaran has spent his last days painting, with the latest work, "The Second Last Day" a self-portrait of him looking skyward.

They will be placed in isolation in the hours before they are taken to a firing ground, where their hands will be bound to a post and they will be given the option of standing, sitting or kneeling before the firing squad.