Put your HTC Vive on and when you are ingame press the MENU button on the hand controllers to open the steam overlay. Activate the trainer as usual with your keyboard. Trainer options will now be drawn as buttons. You can also mute specific hotkeys by changing the hotkey you want to mute to 'NONE'. You can use CTRL-H to re-activate the Hotkeys as well.
To temporarily disable the Hotkeys, press CTRL-H after trainer is activated. Game Speed: Toggl on to affect game speed. Available here: Mafia II Definitive Edition Trainer.