Here's what you can do. . .
On regular graph paper, draw your stars, the way you want them to look on the placemats. Then, on this graph paper http://www.needlepointers.com/displa...hetgraph.shtml
(JUST BE SURE TO USE THE PAPER SO THAT THE BOXES ARE WIDER THAN TALL!), re-draw the picture, box for box.
But these will be done by intarsia or stranding, and the backs will not be "pretty". If you can do satin stitch, it will be more discreet and the backs will look better.