I don't know for the X1, but in the SD1:
You can create via the sampler a new .MSP file. in this multisample file, you add .wavs files with your own samples (cutted from a loop...), and you assign each part of this loop (one by file) to a key, via the sampler...
After all, you can create a new drum kit, with each key assigned to a .wav file....