Here's a link to the quilt I just finished with piano key borders. You can barely see what I did though --- I quilted at an angle starting at the center. Think of an upside down V at the center of the border and work out each way......It's just a small design, don't have to worry about getting the SID exact and doesn't distract from the border itself.
http://www.quiltingboard.com/picture...t-t187680.html