Sorry guys, but I do think this is an intereting question and we all should think about it casually, even for a bit of fun.
A lot of your comments have been very very helpful. In fact, they are correct answers. Since there is nothing 100% certain, let's enlarge the definition of "ensure" to be having 99% chance. What can you do to ensure a 99% acceptance by a med school? Given that you are not a horrible student, you don't have felony record, you DO get a 4 years college degree, you DO have a GPA above 2.0 and a MCAT above 20, I believe that there are many ways to ensure your acceptance.
To build a med school is definitely good. But the cost is too great. To sleep with the dean is much better. Kidnapping the dean with violence is wrong though. I am sure you will not get into a med shcool. You probably end up running the rest of your life.
Other things I believe that you can do practically are:
1. Join the president club or things like that, be a major donor of the school. Donate at least $10 millions. (I think this one is rather easy)
2. Nominated for the Nobel prize.
3. Volunteer at a med center of a med school 12 hrs a day, 7 days a week, for 20 years and write 10 letters to the dean of admission every single day non-stop.
4. Memorize and be able to recite back and forth all textbooks of 1st and 2nd year med students.
5. Place 500 grand pianos outside the front door of the Office of Admission and 100 elephants at the back door.
6. In an med school hospital, get to know every patients' names, illness, treatment and their family members. Memorize all their names and everything about their family history.
7. Save the lives of the board members from a natural disaster.
8. Having every head of every state in the world write you a letter of recommendation.
9. Having N. Korea to threaten US with anthrax unless you are accepted.
10. Find out all the unrevealed malpractices and hidden scandal of all members of the board.