Conventional wisdom seems to indicate that ten times the big blind is the determining level of a stack being either weak or healthy. How do you add in the ante level to a calculation of the health of a chip stack?

Look at the size of the pot with the blinds and antes in it. Your stack is judged in relation to that pot, if you have 10 times as many chips as a pot before anyone enters it then that means you have an M of 10. M is just something it's called, there isn't a good reason why. You should keep your M and other players Ms in mind and change your play accordingly. Harrington talks a lot about this in his books, I advise you read those.