There really aren't any eligibility requirements for the MCAT. You just apply for either the allopathic, osteopathic, podiatric or veterinary field and do the test! You will need to state the reason for doing the MCAT. There are only eligibility requirements for the different courses (allopathic medicine, osteopathic medicine) that require the MCAT for purposes of admission. However usually you have an undergraduate college degree under your belt first so you can fulfil the graduate school requirements.