He has linked with former New Zealand team-mate Kyle Mills to found the Edinburgh Castle Rockers.
It is a T20 franchise that will compete in the inaugural European T20 League, which gets under way in August.
There are a host of household names involved in the ICC-sanctioned T20 league.
Australian great Steve Waugh is heading the franchise in Amsterdam, while Glenn Maxwell has popped up in Belfast.
There will be teams based in Glasgow, Rotterdam and Dublin as well.
"The league was pretty keen to have a New Zealand sort of flavour, and myself and Kyle got approached and we thought it was worth having a crack," McCullum said.
"So yeah, here we are. There’s lots to do between now and then to get things going."
McCullum is a father of three boys aged 11, 13 and 15. He is the managing director of an Auckland construction and maintenance company and on the board of the Otago Cricket Association.
"We’ve managed to announce a couple of players already, which is exciting.
"It’s an exciting opportunity to get involved in growing and developing the game throughout Scotland and Europe.
"And that’s really where we’re looking to add value, is to bridge the pathway between associate cricket, so to speak, and international cricket."
The Rockers have signed Black Caps white-ball captain Mitchell Santner, and former Black Cap-turned Scottish international Tom Bruce is on the books.
There could also be some opportunities for the OCA.
McCullum has briefed the board and the association is keen to explore opportunities. That could mean some kind of player-coach exchange programme.
"We’re trying to work with a number of different entities and Otago Cricket being one where there may be opportunities over the next year or three."
Asked if the Rockers would have a few Volts players lining up for their first season, McCullum said there was that potential, but Mills was taking the lead on recruiting players.
There was also going to be a strong focus on developing local players, he said.
Each team can field only four overseas players.
"So it’s similar to a lot of the different [leagues]. But yeah, like I say, there’s a lot for us to work through with that and we’re just at the start of it.
