Depending on where the scallops stop at/near the corner, could you draw a 45 degree angle through the scallop and mirror the design? depending on how many scallops you have down each side, if it is an odd number you could slightly lengthen the middle scallop to make sure that they finish on the line of the previous border.
Have you checked the pictures of last years BOM to see if anyone did their own thing and scalloped around the corner?
Just looking through previous BOM's have you checked out 2010 Hugs and Kisses? http://www.thequiltshow.com/os/bom2.php/bom_id/12
This was appliqued.