Is there any way I can get this flightstick set up for Ace COmbat 5? Also, is there any way I can set up the original Flight Stick that came in the AC5 bundle? Do I need to set up lilypad for it, or can I just plug it in? Someone should work to build a USB driver for it so all the original usb peripherals can work with it.
A general purpose USB plugin is hard. We've wanted it for a long time

So whats the problem setting up lilypad? maybe you have to play around with the deadzones - but should be no problem overall
If you can not connect buttons to ps2-actions you might need to check the configuration of the joystick-driver/utility.
If the input is acquired correctly by the software then it should not be a problem to use lilypad...