The 37-year-old will join the defending champions for 2021.
The competition has been delayed due to positive coronavirus tests at several clubs.
The tournament will be a key part of the build-up to this year's World Cup in New Zealand.
"Are you f***ing serious?"
The former All Black has been signed as injury cover for their 2021 campaign.
Silver Lake is reportedly close to securing a 15 percent stake that would value the All Blacks at almost $3 billion.
Clayton McMillan will remain with the franchise as an assistant after filling in for Warren Gatland this year.
The Champions Cup and Challenge Cup have been postponed.
The Auckland-based side hope to go one better and take out the 2021 Aotearoa crown.
