Custom Reference Types

If this is something which EndNote X3 already does that I am not aware of, please let me know. From what I can see, it appears that there are a limited number of unused reference types which can be customized by the user (I forget off-hand whether it is 3 or 4). What I would like to be able to do is to have many more unused reference types, so that I can customize them for individual clients or professors who have particular preferences which do not fit in with the usual APA style that I use or so that custom information that is repeated for a particular client can already be filled in and not have to be added each time. For example, in my APA 6th bibliography template, I would like to have several different reference types for the specific types of DVD lectures so that all I would need to fill in is the particular name of the session and all of the other information for that type of lecture DVD would already by in place for me. This would also help with reference styles in which different situations call for variations in the basic style, but there is not enough reference types to account for the potential variations needed. Please let me know if what I am saying is too confusing and clarification is needed.