Fakaosilea and Iusitini were remanded in custody for sentencing on August 29.
Justice Kit Toogood called for a pre-sentence report, and a whanau report for Fakaosilea.
Their guilty pleas followed the earlier sentencing of four people to lengthy prison terms for their involvement in the meth importation, which carries a maximum sentence of life imprisonment.
Iusitini instructed another person to purchase boxes and hire a campervan, all of which were to be used to store and move the methamphetamine once it arrived here.
He also instructed that person to take about 50kg of the drug to a nearby location hidden in the sand dunes.
Malachi Tuilotolava, 26, an Australian national of Tongan heritage, was sentenced last year to 24 years in jail for his role.
He helped purchase and launch a boat from a remote beach in Northland which travelled about 12km out to sea and returned carrying half a tonne of methamphetamine. He also helped unload the drugs.
Three others - Ka Yip Wan, 26, Amoki Matoto Fonua, 32, and another man who has permanent name suppression - have already received lengthy prison terms for their involvement.
Wan was jailed for 23 years, Fonua 22 years and the unidentified man 12 years.
Stevie Cullen, 34, and another person, who has name suppression, have pleaded not guilty and elected trial by jury.
Two boats and cash seized by police during the meth bust could be forfeited to the Crown.