If he's at all serious, then he needs to try reading the Constitution.
In Amendment 12: Choosing the President, Vice President, there's this little clause:
But no person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States.
So, what makes Bill Clinton constitutionally ineligible? Amendment 22: Presidential term limits:
1. No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once.