Hey! Descent pilot
Does anyone know if its possible to play the game over the internet with just the IP
??

Yes, look in the multiplayer. Direct tcp/ip, then one player starts a game, the other types an address into the the box and clicks search for a game. (or something like that, it's been a while since I've played that way.)

http://d3.descent.cx has a tracker for current online tcp/ip servers, if they're empty just try again at a later time.