Amalgamated Builders site foreman Mike Hart said the helicopter was used to place three 600kg smoke extractor fans on the roof.
In the event of a fire in the theatre, the fans would extract the smoke and protect the occupants from asphyxiation.
Mr Hart said it was necessary to use a helicopter and a 53m cable because the placement of the fans was out of reach of most cranes.
"The only other way was to set up a really big crane in the Octagon, which would have blocked off the Octagon for three-quarters of a day.
"This way, we got the job done in 20 minutes."
Regent Theatre general manager Sarah Anderson said the redevelopment was progressing on target and the theatre was due to reopen on August 2.
The fly tower set was being manufactured in Christchurch and there were fears the reopening would be delayed as a result of last week's earthquake.
However, it had been confirmed there had been no damage to the equipment, she said.
