(a) A beneficiary to whom a benefit is payable under this subchapter may by assignment provide that part or all of the benefit be paid in consideration for services provided in connection with the death of the retiree directly to a funeral director or funeral establishment licensed under:
(1) Chapter 651, Occupations Code; or
(2) the comparable law of another state.
(b) The board of trustees by rule may establish requirements for forms, documentation, and procedures necessary for an effective assignment under this section.