There's one way to simulate a metronome: use one Tone on an infinite delay and set the delay period to be a quarter note. Then set the tempo you want and initiate the 'click' by scraping a string or whatever. You may need to experiment with the delay settings - tempo, repeat period, % mix, %feedback, etc. Then jam away to the click on the other tone.
I remember seeing a video from Glenn DeLaune on this forum showing to set up the infinite delay. I couldn't find it right now but I confess I didn't try hard; you may find it with a little more effort. it describes how to set up a 2-sec loop on the X3. You can set it up to loop a click.
Not very elegant, I admit. But you might find it useful.
