"Press & hold" on iPad Monitor

[Simonkbike]

I'm sure it's buried somewhere but can't find how to do simultaneous button presses on Monitor for iPad. 

I'm on a Solution desk (but it's not desk specific so I've put the question here) and I want to swap between Playback cue lists on my remote Monitor.  On the Solution desk I press-and-hold Memories then press the Go button on the chosen cue stack.  The Phantom manuals mention a right-click to hold but that's not an option on iPad, so how do I do this?

Simon