I regrettably inform you that your chances are very slim, outside of actually completing the training required to fly the aircraft.
In this world where aircraft terrorism is always a concern, you would have to have a very good reason to convince the captain why he has to put a complete stranger in the cockpit. To the captain, the stranger is simply someone claiming to have flight experience. To the stranger, it may be an experience; to the captain, it is a routine, daily job, with schedules, policies and regulations to follow.
In my airline, this would be strictly against policy. Even if we were to jumpseat a flight attendant, there has to a necessity to do so (e.g. no rooms in the cabin / broken seat etc.)
There are companies that provide simulator rides to the general public. There are none that provide a jump seat ride as far as I've heard.
Disclaimer: I am not affiliated with the linked company.