Hey ill,
Welcome to OS! I will be glad to help you with a little more information, other than just 'press a button'.
Let's say you have 'X' set up as your Spike. If you are going to score and there is nobody around you, press 'X' repeatedly the second the ball crosses the plane of the endzone. The reason why I say repetitively is because once in a while there will be a cut-scene that immediately follows the touchdown. If the button push does not register before you return to the view of your man in the endzone, you will not be able to see it. It will go into a 'default' celebration. If you are being pursued in the end zone and you have to use a button for a special move to get in there, sacrifice your selected dance for the score and don't worry about the dance. Your first priority is to get that TD. If you are fast enough, you can go right from your TD into your dance. Meaning, let's say you know you have to dive to get in, but the celebration you want is button 'Y'. Once you push 'X' and you are in the endzone, start tapping that 'Y' button as quickly as you can. You should be rewarded with your celebration dance.
It is a fun feature and it does give you more of a personal connection to your player on the field.
UUuuuuu!! I have an idea for a GREAT feature in 2k6! I am going to post it there now!!