He is the partner of Ger Dundon's ex-girlfriend April Collins.
She was present in court this week when O'Neill heard that he will get temporary release for the holidays.
O'Neill, with an address at The Meadows, Murroe, Co Limerick, admitted in Limerick Circuit Criminal Court yesterday that he threatened Jennifer McCarthy that he would burn her mother -- Deirdre O'Donovan -- from her home on July 25, 2011.
Deirdre O'Donovan is the sister of Dolores McNamara who won €115m in the Euromillions jackpot in 2005.
O'Neill pleaded guilty to the offence before Judge Carroll Moran after a trial hearing evidence of the same crime collapsed on Wednesday.
The trial halted after Jennifer McCarthy told the jury that another man, Dean Hehir (26), who was with O'Neill, admitted on Wednesday to threatening to damage her home.
During her evidence, she said Hehir and O'Neill were parked in a BMW alongside her home in Limerick.
Ms McCarthy, who was minding her children, said she could hear them "roaring up" at her and calling her 'piranhas'.
She told Judge Carroll Moran that her family -- the McCarthys -- are called piranhas.
She said Dean Hehir said to her: "I'm going to burn you and your kids out of it," while O'Neill shouted: "I'm going to burn your mother out of it."
Ms McCarthy said her family were terrified as her father had burnt to death.
Before the trial began again in front of a new jury, O'Neill -- who has been in custody since January -- pleaded guilty yesterday before Judge Moran.
His barrister, Brian McInerney, successfully applied for Christmas bail for O'Neill.
Judge Moran acceded to a request for him to be freed from December 21 to January 2.
The court stated that O'Neill, who has 36 previous convictions, must reside at Lenihan Avenue in Limerick.
O'Neill will be sentenced with Hehir, of Collins Avenue, Ballinacurra-Weston, Limerick, next month.