Pointing an object to the mouse cursor.

Essentially, I'm working on a mechanic for a jousting-type game. I have a lance which I want to point to the mouse cursor. I'm thinking that I should use a LookAt command to do this, however I'm unsure how best to implement this. The camera will be first person placing the player as the jouster, looking down the field towards the enemy jouster. If anyone has any ideas of how to achieve this I'd be most grateful.