You mean it doesnt recognize them at the joypad setup, I assume.
The X360 pad doesnt use Directinput, it uses XInput (I believe) instead. I wouldn't be surprised if it would not work at all. I wouldn't hold my hands for support from the emulators side either (its a japanese emulator - the xbox isnt exactly popular there). So unless some compatibility layer is released by Microsoft that converts XInput calls to Directinput, the x360 pad will most likely never work with SSF.