I ended up just writting a small metroscript like
IF GT IN 500 : MUTE 1
IF GT IN 500 : MUTE 2
IF LT IN 500 : UNMUTE 1
IF LT IN 500 : UNMUTE 2
This way, with the metro running at fastest possible interval, it'll check every 10 ms if i have gate high or low on the IN...
Not very elegant but it works for now