Any way to bulk load users?
 

I'm new to vBulletin and looking for a way to integrate other systems with vBulletin to accomplish single sign-on. I'm mystified by the API documentation -- it doesn't really provide much direction on how to get this done.
Short of coding to the API is there any other way to import users? For example is there a way to load users in bulk - from a .csv? It seems to me this would be a common requirement. For example, in connection with a product launch I'm going to have large numbers of new users and need a better solution than adding them manually one at a time.
I've looked at Impex but it appears to be for the purpose of importing or migrating from other forum software. If there's a way to use this system to import users only I would be interested.