The process will be quick once you have an appointment with an American consular officer.
Here's a summary of the procedure according to FilipinoWeb.com:
As an American consular officers are specially prohibited from certifying that any U.S. citizen has the capacity to marry, the Philippine government has agreed to accept as substantial compliance with the Philippine law an Affidavit in Lieu of Legal Capacity to Contract Marriage (â€śaffidavitâ€ť). The Affidavit attests to the absence of any legal impediment to the marriage and is sworn to before an American consular officer. Therefore, u.S. citizens wishing to marry in the Philippines must appear personally before a consular officer, either at the U.S. Embassy in Manila or the U.S. consulate in Cebu City and complete the Affidavit concerning their own capacity to marry. There is a $10.00 service fee, subject to change, for the notarial service.
At the time a U.S. citizen appears to execute the Affidavit, he or she must present the following:
A. Proof of Citizenship. Examples of sufficient evidence of U.S. citizenship are (1) current registration as U.S. citizen at the Passport and Citizenship Office of the Embassy or at the Consulate, (2) a U.S. passport, (3) a birth certificate issued in the United States or a record of birth abroad issued by a U.S. Embassy or Consulate, together with identification bearing a picture or a physical description or (4) a Certificate of Naturalization.
B. Evidence of Termination of Previous Marriage (s). If the U.S. citizen has been previously married, evidence of termination of the previous marriage, such as a certified copy of the final decree of divorce or annulment, or a certified copy of the death certificate of the deceased spouse must be submitted.
C. Parentâ€™s Consent or Advice. Under Philippine law, the legal age for marriage is 18. If the contracting parties are between the ages of 18 and 21, they must present written consent to the marriage from their father, mother or legal guardian. Any contracting party between the age of 21 and 25 must present written parental advice, i.e., a written indication that the parents are aware of the coupleâ€™s intent to marry.
Military Approval. An active member of the United States Armed Forces wishing to execute the Affidavit must present a letter of approval of the marriage from the appropriate military authority. Military personnel NOT assigned in the Philippines are also required to obtain their authorization from their respective commanding officer. Military members are encouraged to plan well in advance of the intended wedding date and to discuss the requirements with their own command personnel office.