Another solution (which I prefer) is to use PPJoy to create a virtual joystick. Basically, it sets up a joystick driver that is actually powered by your mouse. This lets you have freelancer-style mouse control... the only snag is that there is no HUD indicator to say where your mouse currently is, and you will frequently start a mission with your "joystick" off-center (Causing you to start turning first-thing). The lack of indicator isn't a problem, really, since it's easy to tell if you're turning or not, and the mission-start issue can be overcome with a bit of practice.
The other nice thing about this solution is that it works for any game with joystick support but suboptimal mouse support. So, you can use the same virtual joystick to get Freelancer-style control for Descent as well (for example).