I've heard of one called Joytokey, but supposedly it's kind of complicated compared to Xpadder, though I personally haven't tried it.
Just curious, why not use Xpadder? Does it not work for you or something? I have an accurate Xpadder profile for COD4. Other than that I don't know what to tell you because I've never used the PSX emulator, ePSXe is the one I've used and my 360 controller configures just fine with the input plugin. One more thing, are you using the XBCD drivers for your 360 controller, it's soooo much better than the default one and it's much easier to configure your controller for different games/emulators.
Edit- Although if you're using a wireless 360 controller the XBCD drivers won't work unfortunately.