Multi-part Primary Key

I've gotten myself into an interesting situation right now.  I have this app with a large installed base.  It was written in Paradox, and makes use of multi-field primary keys throughout.  We've just moved it to SQL Server, and we'd love to use Object Builder to generate active record objects.

The problem that I'm running into is that I'm not enough of an XSL wizard to manage multi-part primary keys.   So I'm asking any XSL wizards out there who are familiar with Object Builder to see if they can take a stab at this problem.  There's no common element among these fields that can be used as a clue, other than their presence in the primary key.