I possess the original letter that is published here from the Lubavitcher Rebbe ZT”L in response to the question of the source for the minhag.
http://www.hebrewbooks.org/pdfpager.aspx?req=15952&st=&pgnum=345
As the Rebbe notes, the minhag is not found referenced in niglah. I personally hesitate from accepting the reference from Poliakoff above with any seriousness, as he clearly avoided nistar. No clue whether he is otherwise reliable, but is certainly not authoritative about matters outside his domain.
For those who have the mesorah of this minhag, they should follow that heritage. I am not among those who would push it on someone who does not have such a mesorah.