The 3of9 font that Kate mentions might do the job for you. You can download it for free at:

http://www.squaregear.net/fonts/free3of9.shtml

However, it depends on the handheld scanners you are using. The 3of9 font uses a special character (i believe an * ) to signify the start and end of the code. Unfortunately, it isn't possible at this point to add that character through a formula field (like in Excel, using a concatenate formula) though that would be ideal. I've been told that there are some handheld scanners that can overcome this limitation, but i've tried on a couple with no success.

If your scanners don't work straight up, you could try placing a text field with an asterisk (using the 3of9 font) immediately before and after the order number.

Or you may want to get in touch with the guys at RF Pathways. They are Adagio Developer Partners with a number of barcode warehousing solutions that interface into Adagio.

http://www.rfpathways.com/softrak.htm