The Normal.gxt will retain certan chages you have made such as chages to the location of toolbars or what tools are present on a toolbar. If a file with the name Normal.gxt doesn't exist at this location on the startup of ArcCatalog it will recreate this file with all of the default settings as if opening ArcCatalog for the first time.
I would suggest that you rename your current Normal.gxt and then move the new one over. That way you could always go back to the previous one if necessary.
Optionally you could open ArcCatalog with the gxt provided with the ArcScript and export the forms and then delete the provided gxt. Then open ArcCatalog with your old gxt and add 2 new UI button controls to handle the showing of the forms.
When you open ArcCatalog with the ArcScripts gxt and then open the VBA editor you'll notice code in 2 locations:
Normal.gxt > ArcCatalog Objects > ThisDocument
- this is the current UI controls click event handler code to show the forms.
Normal.gxt > Forms
- this is the forms and associated code behind
Hope this helps!