title: in entity framework code first, how to use KeyAttribute on multiple columns
body: <p>I'm creating a POCO model to use with entity framework code first CTP5.  I'm using the  decoration to make a property map to a PK column.  But how can I define a PK on more then one column, and specifically, how can I control order of the columns in the index?  Is it a result of the order of properties in the class?</p>
  
  <p>Thanks!</p>