The trick to the "3D" in this is more about trompe l'oeil than anything else. It isn't true 3d - it is just correctly positioned layers with shading that makes your eye think there is a 3rd dimension. To edit the text - just type on the layer etc. Nothing to it really and it really isn't that special. Obviously if you use larger or smaller text you will have to increase or decrease the layer styles accordingly.
As usual you may use these for personal and commercial endeavors - BUT, do NOT redistribute without express written permission.