hey maxine - time to get out your crochet hook
just do this where you want the embellishment . . . skinny strips of fabric also work great . . . or use fishing line for the invisible look!
if this young girl can do it - you can too! http://www.ehow.com/video_4468282_ma...lip-flops.html
with this method - i don't think you'd have to wrap the back strap . . . unless i'm not picturing in my muddled mind what you're trying to do!
edit - hahah - just saw the pic you attached . . . you could start this just above where the 2 straps meet in light pink . . .