[Opserty]

If it involves customising a default vBulletin template it is best just to provide instructions to the User as to what to do. Most people will already have other mods installed and customised styles (especially if they are downloading mods), if you start messing around with their styles automatically then they are going to get annoyed when their vBulletin falls apart.

Just provide instructions to modify existing templates and if you are making new templates insert them into the MASTER STYLE and associate the template's product with your product.