Heres how this all went down (evidently only started a few weeks ago)
Mark Miles and Zak Brown were friends before one became President & CEO of Hulman & Company and the other took over McLaren. But together they figured out a way to help boost the Indianapolis 500's profile and check off a box on a two-time Formula 1 champion's bucket list.
"I got a call from Zak a couple of weeks ago and he wondered if we could put a Honda deal together so Fernando could run in this year's Indy 500," Miles told RACER.com. "I said we would move heaven and earth to make that happen.
"So I contacted some Honda teams and he contacted one, but we couldn't find an engine. And then we got lucky."
Miles reached out to Stefan Wilson, who had been working on his own program for Indy, explained his dilemma, and suggested maybe there was a way the younger brother of the late Justin Wilson could help: give up his seat for Alonso next month, and let IMS add to the value of his program for 2018.
"As much as he wanted to run the Speedway this year, he was looking out for the greater good of IndyCar," said Miles. "Quite a gesture."
Brown then approached the McLaren board and Honda of Japan to make his pitch, and thus began non-stop texting between Miles, Brown and Michael Andretti.
For Alonso, Indy may be a daunting task since he's never been on an oval, but at least he'll have a chance to be competitive for the first time in 2017. His Honda F1 engine has under-performed and stuck him in the back of the pack - but his Honda IndyCar engine has won the first two Verizon series races.
"It's an amazing story," said Miles. "Fernando wants to go for the Triple Crown [Le Mans, Indy 500, Monaco], and McLaren is returning after a 38-year absence and all that history.
"Alonso has never been on a superspeedway, but he'll get a private test day at IMS and all that practice in May - and Alexander (Rossi) showed a rookie could win last May. The heroes of this story are Alonso, Zak, Michael and Stefan [ED: Along with Wilson's sponsors Gap Guard, Dale Pelfrey and Indiana Donor Network, who accepted the new arrangement]. And I think it's going to be a pretty cool story, and another great month of May."