§ 159-a. Disability program. Notwithstanding any other law, rule or regulation to the contrary, where an agreement between the state and an employee organization entered into pursuant to article fourteen of this chapter so provides on behalf of employees in positions serving in the collective negotiating unit created by chapter four hundred three of the laws of nineteen hundred eighty-three, the director of employee relations is authorized to establish and implement a disability program that will provide long term income protection for such employees and the president is empowered to establish regulations to effect such implementation. No regulation shall be adopted, repealed or amended, and no other action taken with respect to such employees or such implementation without the approval of the director of employee relations. Notwithstanding any other law, rule or regulation to the contrary, any employee who participates in or is covered by a disability program authorized by this section shall receive retirement service credit not to exceed six months during the period that he or she is receiving the short term disability benefit under such program on the same basis and at the same rate as such employee would receive such credit were he or she on sick leave at half pay for the period of time for which such employee would have been entitled to such sick leave at half pay had the sick leave policy supplemented by the short term disability program remained in effect.