Just quickly playing around (5 mins) with the Kendo it doesn't appear to be evaluating EAN13 properly.
9780671027032 Dale Carengies How to Win Friends and Influence people
Take the first example on the Kendo dojo page and change it from ean8 to ean13 and paste the above barcode in. The photo of the cheese loses its barcode suggesting that the barcode is invalid. If however you delete the check digit (the last "2") then it generates the barcode but without the check digit
If you do the same experiment here http://lindell.me/JsBarcode/generator/ then the barcode will generate both with the check digit in place and without the check digit - however if you don't type the check digit in this case it will calculate the check digit and add it to the barcode.
So it looks like the Kendo has some bugs in it at the moment.
How would I go about implementing this http://lindell.me/JsBarcode/generator/ and then calling it within AwareIM?