My sole experience of this nature, as best I can recall, was a European applicant who did a PhD as an International student and then applied.... having a PhD from a US school was acceptable at my school which usually requires a bachelor's degree from a US or Canadian school. On the other hand, that takes about as long or longer as an undergrad degree and might not be a feasible alternative for you, fasttortise.
However, your case is a bit different. First, it looks as if you are going to need to get up to speed in physics, biology, chemistry (including organic chemistry) in order to do well on the MCAT. That sequence usually takes 2 years along with some upper level courses that are usually required or highly recommended (biochemistry, genetics, statistics, calculus, psychology, English). It might be possible to shorten this and take the MCAT after your first 12 months of study and apply in the following cycle but that is going to be grinding.
Taking exams and earning credit for what you already know could give you a head start toward a bachelors from a US school. Here's a search engine that will help you find a school that wil accept scores toward a degree:
http://apps.collegeboard.org/cbsearch_clep/searchCLEPColleges.jsp
This is more information for veterans regarding the College-Level Examination Program:
See
http://www.collegeboard.com/student/testing/clep/veterans.html
There are 2,000+ schools on the list so it is likely you'll find one near you. Then contact the school to find out more about how a returning or non-traditional student can earn a degree.
Could you consider relocating? To do what you want to do in a reasonable length of time is going to require excellent time management skills and reducing commuting time could be very important. Furthermore, your best chance of learning the material and earning good grades may preclude working at your current job. Keep in mind that average grade point averages for admission to US med schools are between 3.6 and 3.7 on a 4.0 scale where A is = 4 and B = 3.
Have you worked as a health care provider of some kind? If not, you are going to need to have work or volunteer experience with sick and/or injured patients in a clinical setting (hospital, ambulatory care or rehab setting) to convince admissions committees (adcoms) that you know what you are undertaking.
Finally, do get used to asking for help. In medicine, they call it a "consult" with the emphasis on the first syllable. Using one's specialized knowledge, skills and ability to help others can be enjoyable and it is why I tend to hang out here (I also find it informative and understanding the process from the applicant's point of view makes me a more empathetic member of the adcom).
If you mention my name in a post, I'll usually respond within 12 hours. Someone has a "bat signal" they use to call me (thus my location in the Bat Cave and the picture on my profile page) but just putting my name in a post (no space between the y and M) will usually draw me out.
