I think all the vendors are present in the OS itself.. you just need to unlock them. Here is the link on how to unlock other vendor themes.
http://www.blackberryforums.com/gene...ee-memory.html
In that process, there is a step where it says the vendor themes are listed as "net_rim_theme....".. just do not delete those files from the installation folder.
You should then be able to use the other vendor themes.