You can download it from here:
ftp://ftp.roland.co.uk/ProductSupport/HPD-10/
It can use foot-switches to trigger sounds, it's not unlike assigning a sound to a pad (page 9 of manual).
You need to tell the HPD-10 the 'type' of input to be used, a foot-switch, or a trigger.
It's part of the set-up menu (P24 of manual).
I would point out that a real trigger will offer velocity sensitivity, where as a foot-switch is set value.
It's also worth pointing out that the polarity of the foot-switch is changeable, allowing any non latching foot-switch / sustain pedal to work, handy if you have one lying around.
It might be worth looking at the DP-2 pedal, might be easier on the feet, as the FS-5U switch sits quite high on the pedal. It was designed more as a effect control switch.
