youre choosing a hard way u can use simple ir LEDs instead but if u have to use barcode reader u definitly need the data analyser unit to work with the 16 bit that the analyser reads.maybe an AVR will be good idea
The method with adopting the barcode scanner would be very elegant, because you can not only detect the line, but also estimate how far off you are. That would allow you to use a better control algorithm to follow the line (e.g. PID).
However, this is not the simplest method. I’ve never heard of anybody doing the line following this way, although this should not be discouraging you. You should take a barcode reader (I would suggest a fairly old and primitive one), take the cover off and examine its signals with the scope.
P.S. If you want to have a “canned” solution for line following, take a look here **broken link removed**