I don't know if anyone is still instered, but with the troubleshooter you can play with both guns in hotd, hotd2, hotd3, vcorp and vcorp2.
After install troubleshooter, be sure that you don't remap the keys of the games, and the keyboard is selected to play it.
Go to troublehooter (Lightguns), and select the player 1 and 2 devices. I don't remember what I set here, but you can try some (I think for the Topguns is something like USB Mouse...). Of course, select diferents devices for each game.
Finally, enable the game you want in the 'Games' tab.
Run the game you want.