You have to use an external pedal to access the hold function which is assigned in the control module, there are a couple of patches set up already for the hold function which is not exactly looping. I recall messing with it years ago and abandoning it as not something i would even try live.
● dH (delay hold)
The foot switch controls on/off of the delay
hold function. When a patch using the hold
function is selected, pressing the foot switch
will activate hold, causing the current delay
sound to be repeated (see illustration at the
bottom of this page). Pressing the foot switch
once more cancels the hold condition, and the
delay sound will decay normally.
To use the hold function, an effect type that
supports the hold function must be selected in the
patch. For details, see page 33.