Creating a Product 
To create a vBulletin 'product' that can be downloaded and installed by others, there are several stages to be performed.

In summary, they are these:
  1. Add a product record and title it accordingly
  2. Add plugin code for the product
  3. Add templates and phrases for the product
  4. Add options for the product
  5. Add control panel navigation entries for the product
  6. Add bitfield permissions for the product
  7. Export the product XML file
Brad Watkins 06th Jan 2006, 06:53pm
You can find a lot of information related to making modifications to vBulletin with the plug-in system at vBulletin.org

http://www.vbulletin.org/forum/forumdisplay.php?f=184