I've tried to fail both pumps for either the system A or B hydraulics, and although I get an indication that the failure has occured in the failure control panel there's nothing happening in the cockpit itself. I get no master caution or anything. What can I do here?

I share your question and unfortuantely do not have an answer (as apparently did no one else as well).I see an indicator on the overhead panel for Standby HYD system activation but no switch to actually activate it.