You don't need "tabs" on your SCAL file, I think we just need to put our letter on either the left or right per the list.
The punch is hard to find, if I remember correctly.  It's with the rolodex stuff, but easy to overlook, because it's small.  It's just a small black square, kind of flat.  
If you can't find one, Hope, I'm happy to mail mine to you for your use.