He said it was the raids on his Auckland house which had motivated him to enter politics.
"The New Zealand Government made a mistake radicalising me because I know all their dirty tricks."
He also said the New Zealand media had vilified Mr Harawira.
"He [Mr Harawira] is actually quite cute."
He said New Zealand was lacking in "the basic infrastructure to compete in this digital economy".
"It [New Zealand's future] does not lie in farming."
In order to pay for improved digital infrastructure and free tertiary education - two Internet MANA policies - the party would introduce a capital gains tax, Mr Dotcom said.
"By the way, on the record, I did not hack Whaleoil," he added, in reference to allegations he had gained access to Whaleoil blogger Cameron Slater's emails. MANA's Ikaroa-Rawhiti candidate Te Hamua Nikora also spoke to an emotionally charged crowd.
He said he had been mustering support since he came second to Labour's Meka Whaitiri in last year's Ikaroa-Rawhiti by-election.
After a freestyle rap, he gave a humorous and energetic talk, which drew laughs from the audience.
"This is history in the making - I'm in mourning for National, because every vote for Internet MANA is a nail in National's coffin," Mr Nikora said.
He said he would open a youth centre in Flaxmere if elected, and also expressed opposition to the proposed Ruataniwha Dam.