Mergers and Acquisitions (M&A) - Career Switch Path

I'm exploring M&A as a career switch path. One way is to go to a good law school, make partner at a good M&A law firm, and proceed from there.

That may not be very accessible in mid-career.

Another way I've heard about is to get an MBA in finance. I've also heard that audit is a good way to go - that would depend on getting hired as an auditor.

This link mentions another credential: http://www.icaew.com/index.cfm/route/164292/icaew_ga/en/Qualifications/CFq/Corporate_Finance_qualification