You can politely tell people in front of you that you have a tight connection and please let you squeeze by. It's as simple as that. But don't expect everybody should comply with your request. Welcome to the real world.
AND, in fact, this situation is exactly why you should buy a front seat in advance. The airlines are doing exactly what they want to happen: get customers to pay for more convenience, comfort and enjoyment. There is an extra cost for these.