you gotta know other CEOs from serving on Company Boards, or be extremely good friends with someone who is, AND have all the skills necessary to do the job easily.
about references like this: getting references for this kind of work can be difficult, because to someone of that economic tier, keeping your reputation up and your network connections strong are the most valuable secondary skills you can have. vouching for someone who would not be a good CEO would kill your reputation, so it doesn't really happen among the highest tier of companies. Also, boards usually vote on these things, even for interim positions, so .. ya gotta know other CEOs from serving with them on boards.
good work of you can get it, I'm sure.