What am I entitled to if my ex-employer continues to withhold payment that he owes me for an extended period?

This response is without going to the hyperlink.  You can inform him that your pay should be made either weekly or bi-weekly.  If employment is terminated, the employer shall pay the  wages  not
  later  than  the  regular  pay  day  for the pay period during which the termination occurred, as established in accordance with  the  provisions  of  New York Labor Code Section 191. If requested by the employee, such wages shall be paid by mail.

Pursuant to New York Labor Code Section 197 regarding civil penalties, any employer who fails to pay the wages of his employees or shall differentiate in rate  of  pay  because  of  sex,  as
  provided  in  this article, shall forfeit to the people of the state the sum of five hundred dollars for each such failure, to  be  recovered  by  the commissioner in a civil action.

Further, you can inform him there may be criminal penalties, as well, pursuant to New York Labor Code Section 198-a, wherein he could be guilty of a misdemeanor and fines between $500.00 and $ 20,000.00.