Each employer may adopt rules to implement this chapter including but not limited to:
(1) The method of filing an election to accept an adjustment in earnings and revocation of the election;
(2) The effective date of an election;
(3) Changes in the amount of the adjustment in earnings; and
(4) Selection of the insurance company or companies from which the annuity contracts are to be purchased or to which payments into a qualified custodial account are to be made.