46 year old CPA wants to earn reputable doctorate - need advice
Age >40 not a problem

I am a faculty member at a top-50 business school.  We would definitely consider candidates who are your age.  In fact, your age is something of an advantage in that you would certainly have substantial real-world experience.  

... but we train researchers

Your stated primary goal of teaching would definitely be a strike against you.  Top PhD programs are primarily in the business of training people who have research as a primary goal.  The training we offer is primarily how to create new knowledge, as well as socialization into the institutions of academic research.