We have imported a collection of closed cases from another system.  We want to link those cases to accounts and sometimes contacts.  The cases have fields that can be found in the Accounts (UserID) and Contacts (License Code), but I cannot figure out a way to assign all the cases (there are 1000's of them) to accounts at once rather than one at a time.

Since bulk imports exists, I have assumed that bulk linking exists and I simply can't find the correct KB or article.