Junction table with additional payload columns in EF4 CTP4 Code First -

i have following tables:

wopartlist (defines parts have 1 or more part_size) wopartsize (defines sizes have 1 or more part_size)

part_size (junction table addt payload columns such sku, on_hand etc...)

here poco classes dal:

    // real world scenario:      // partlist                related part_size     related partsize       //     // #8 stainless lag bolt   sku- 87234018            size- 2 x 1/2       //                         on hand- 214      //                         on order- 12       // #8 stainless lag bolt   sku- 87234199            size- 3 x 1/2       //                         on hand- 81      //                         on order- 18        // #10 stainless lag bolt  sku- 87237835            size- 1 x 1/2       //                         on hand- 11      //                         on order- 14       // #10 stainless lag bolt  sku- 87237835            size- 2 x 1/2       //                         on hand- 11      //                         on order- 14       // #10 stainless lag bolt  sku- 87237835            size- 3 x 1/2       //                         on hand- 11      //                         on order- 14       // idea able create size once , use many times     // many different parts... need keep specific statistics     // each size of part...      // how tell model part_size many-to-many junction table     // between wopartsize , wopartslist ?   public class wopartsize {      public int wopartsizeid { get; set; }     public datetime tadded { get; set; }     public string size { get; set; }      // nav collections     public virtual icollection<part_size> parts { get; set; }  }   public class part_size   // junction table {     public int wopartsizemmid { get; set; }      public string part_no { get; set; }     public string part_descr { get; set; }     public string sku { get; set; }     public decimal cost_each { get; set; }     public decimal price_each { get; set; }     public int on_hand { get; set; }     public int on_trucks { get; set; }     public int on_order { get; set; }      // put icollections<> here ?  }  public class wopartslist {      public int wopartslistid { get; set; }     public datetime tadded { get; set; }     public string part_descr { get; set; }      // nav references     public virtual woparttype parttype { get; set; }     public int woparttypeid { get; set; }      public virtual icollection<part_size> sizes { get; set; }  } 

how configure junction table ? annotations ? fluent api ? main trouble getting additional payload fields in junction table... otherwise let ef generate table me , have no poco class...