well I do not use vb3 anymore havent for quite some time. Was never a vbulletin hack author so I can only guess.
Where you not able to change a style in vb
and it would put in the url something like styleid=6 or something in the url
If thats the case you could try putting in our global file pp-inc.php something like this up the top of the file under the error_reporting line
Content visible to verified customers only.
Make sure the numeric id is whatever the styleid of the style you want the gallery to use. I can not offer any support on this as I cant try it etc but just trying to remember how they did it.