As to the homestead, the waiver must be by a separate instrument in writing, subscribed by the party making the same and attested by one witness. If such party is a married man, such waiver shall not be valid without the voluntary signature and assent of the wife and acknowledgment by her before an officer authorized to take acknowledgments in the form of the individual acknowledgment prescribed by this Code. If such party is a married woman, such waiver shall be executed only in the mode prescribed by Section 30-4-12 for the alienation of her lands.