The 2009 trial before Justice Robert Dobson was told McCallum and Rippon were patched gang members, and Ahsin and Rameka gang associates, when they had embarked on a "completely mindless and violent attack" on Mr Kumeroa, who had no gang connections.
Mr Kumeroa was murdered on September 23, 2009.
McCallum had had an altercation with a rival gang member earlier in the day, and there had been an element of premeditation towards that gang, Justice Dobson said.
Mr Kumeroa had been drinking, and had been wearing a red hoodie that belonged to his partner when he had walked home alone along Cross St on the night of the attack.
Ahsin had been driving a borrowed car when she and her associates had driven past Mr Kumeroa, he said.
She had reversed the car and Rippon and McCallum got out and attacked him.
McCallum had felled Mr Kumeroa with a small axe with two blows to the side and back of his head. Justice Dobson described it as a callous, brutal and unprovoked attack.
He told Ahsin at the sentencing that two female voices had been heard yelling encouragement on the night of the attack.
There were no witnesses that could identify the occupants of the car.
Defence counsel for the women suggested that the actions of the woman or women who had called to the men to get back into the car indicated that whoever spoke was trying to stop matters going as far.
That was the "evidential foundation on which the appellants rely for the appeal point", the documents said.
It was suggested the judge should have raised that point with the jury in relation to providing assistance and in relation to any common purpose.
Rameka and Ahsin went to the Court of Appeal in November 2010 and failed to get their convictions quashed. They did manage to have their minimum periods in prison reduced to 10 years.
