I have several people using Outlook for Contacts, but Lotus for email & calendar...
I just modify the desktop mgr config to sync the address book with the Outlook PST file, and the rest to Lotus. Works fine.
Once the contacts are on the BB, I change desktop mgr again...this time I tell it to use the Lotus Notes address book. Now all the Outlook contacts that are on the BB will get pushed into the Notes address book.