most scanners are 'keyboard wedges', which effectively sit alongside in parallel with a keyboard or in place of a keyboard. input from the scanner is treated as keypresses. but that depends on the precise make of scanner.
the only real trick is to make certain that the text box to receive the input has the focus. you can do that through the user pressing,say the tab key. in a keyboard less device you can supply a preprinted barcode with various codes which equate to commands on (eg open form blah, set focus to the product input box)
depending on the devoice soem bardoce scanners encode carriage returns on scan, some don't... so read the help files for the barcode device you are using.
Ive seen laminated sheets with command codes that the user scans to bring up the right form. A simialr technique is used in some petrol (gas) stations in the UK, where the till has a pre printed laminated sheet for things like coffee vending machines, supermarkets often have the weeks special offers as an addendum sheet
I'd rather be riding on the Tiger 800 or the Norton