Treatment of injuries at the expense of the employer may also include, either in addition to or in place of medical, surgical, and hospital services, as specified in Section 3209.5, any other form of therapy, treatment, or healing practice agreed upon voluntarily in writing, between the employee and his employer. Such agreement may be entered into at any time after employment and shall be in a form approved by the Department of Industrial Relations, and shall include at least the following items:
(a) A description of the form of healing practice intended to be relied upon and designation of individuals and facilities qualified to administer it.
(b) The employee shall not by entering into such an agreement or by selecting such therapy, treatment or healing practice, waive any rights conferred upon him by law, or forfeit any benefits to which he might otherwise be entitled.
(c) The employer and the employee shall each reserve the right to terminate such agreement upon seven days written notice to the other party.
No liability shall be incurred by the employer under the provisions of this section, except as provided for in Chapter 3 (commencing with Section 3600), of this part.