I think Datawedge 3.3 was the last one that will work on that device. You will probably want to update to that version if you don't have it already. There is a way to set up that version so that it has profiles defined by what app has focus on the screen, so if you don't have both RFID and scanning in one app, you could set up a profile for your RFID app that has barcode input disabled. This would automatically disable the scanner when your app is in the foreground.
If you really need the ability to turn Datawedge off and on programatically, there is also an API that you can download for this version of Datawedge on the same link.