Emulated Roku - Button Hold to repeat

Hi, wondered if anyone could provide any guidance on how I can programme a push-and-hold using Emulated Roku device buttons. I’ve mapped all of my keys, however would like to be able to push and hold right/ff etc.

I’ve tried repeating a command from keydown to keyup but I’ve been unable to make this work reliably. I feel like I’m missing something obvious!

Thanks, Alex