Hello Stefan,
Thanks for asking! To be honest, I don't remember exactly how we've recorded each effect, since it's almost 14 years ago. But pressing the pedal would make sense to let the chain vibrate more effectively, for example. The screws spread the strings, so the dampers could be blocked, pressing the pedal could be a workaround too, maybe occasionally half pedaling has been applied, solutions like that...
I hope that helps a bit!
Best, Michael