Mmm...I dunno...that story seems a little off for some reason. I have trouble believing the chalk custom preceded the names. I'll investigate though and see what I come up with.
Yeah, after some digging I think Mr. D’Ambrosio accidentally passed on some incorrect research. The Western names Caspar, Melchior, and Balthazzar are early:
http://en.wikipedia.org/wiki/Biblical_Magi
“The names of the Magi derive from an early 6th century Greek manuscript in Alexandria, translated into the Latin Excerpta Latina Barbari: [quoted in footnote: At that time in the reign of Augustus, on 1st January the Magi brought him gifts and worshipped him. The names of the Magi were Bithisarea, Melchior and Gathaspa.]”
The chalk initials came from those names and not the other way ‘round.