Need help with rudder pedals and Jane's F/A-18 flight sim

I have some old racecar gas/brake pedals that can double as rudder pedals for a flying game. I hooked them up to the gameport on my soundcard and then plugged my joystick into them but I’m having trouble getting them to work. When I install the joystick drivers in the control panel (winxp), there’s an option to “enable rudders and pedals” but if I check that box it doesn’t work. It shows the device as being “not connected.” So I leave the box unchecked and start my game (Jane’s F/A-18), and the pedals work. But of course, to my dismay, they don’t work properly. The right pedal raises the nose of the airplane and the left one lowers it (maybe it’s recognizing the pedals as another joystick?) As far as I can tell, there’s no way to tweak this in the game. So, does anyone have any ideas?

Sorry for rambling on so much but it’s kind of hard to word a question like that. And mods, please move this if you feel it’s not up to GQ par.