I did a barcode app once.
The software that came with the barcode reader included a special font. The font was the barcode. There were actually 4 or 5 fonts, some would have the text equivelant of the barcode underneath it, some were just the bars.
Anyways, I used the label wizard on some Avery peel-off sticky labels, and treated the barcode just like regular data, but the numbers/letters are formatted as bars. Kind of like wingdings, except with bars.
We shopped around for barcode readers, and this seemed to be the standard approach.
HTH,