Type what is needed to scan in Microsoft Word or Excel such as Constituent ID #, fund name, gift amount (25 for $25.00).  Put an * before and after each piece of data.  Then change the font to 3 of 9 Barcode.  

In Microsoft Word, an * before and after a string is a command to boldface it.  Turn off that function by going to Tools, Auto Correct, Auto Format, Turn off (*bold* and italic for real formatting).

NOTE: This process requires formatting the barcode exactly as shown in How are barcodes configured? Manually creating barcodes is beyond the scope of support. The supported method is to exporting or printing them from Mail.