Well apparently when you start a game in Rainbow 6: Vegas and you see “GI John Doe Mode” pop across your screen you start to think what the hell…?? well i did some research and came across theses directions to do that game mode…

Here is what you do when you host a game online, start the game, next hit the start button; hold L2, and then press L3(2), X, R3(2), O, L3(2), square, R3(2), triangle.

You must do it the correct way or you will restart the match… my advice would be to try it with some of your friends in a room at first and if it works do it on a 10+ match.
If you have done it the right way then Alpha team’s / bullets turn neon blue, Bravo Team’s bullets turn neon red.

Now if and when you are playing Rainbow Six 3: Black Arrow and you want the laser bullets / trails you would do the following code to activate them…
Press Up, Down, Up, Down, click Right Analog-stick(2) during game play.
Just to let everyone know… I have not tried theses codes because I do not host matches I just play against friends I know and have met online. So if the above codes work please leave a comment and let everyone know…