I know I said this in your other thread, but you CAN NOT find your secret trainer ID number, because it is a secret value.
The only possible way would be via a cheating device, but I have no idea what codes you would use, and discussion of cheating devices and related topics is prohibitted {sp?} on these forums.
In my opinion, it isn't worth trying to find you secret ID, and to use it to change the ID of pokemon that do not belong to you, (Like you were saying in the other thread) it's too risky and complicated.
~Aquarelle