How to search users, categories and channels by partner related data

Hello,
I'm looking for a way to programmatically bind MediaSpace categories and channels to my current LMS organizational units (OUs).

1) Is there any way to, say, add to a MediaSpace category/channel some ID value that matches an ID of an LMS OU and use this ID in query search requests?
2) It there any way to bind MediaSpace user to an external LMS OU specifying OU's ID somewhere in user's attributes and later search all users that have the same ID value?

Thanks in advance!