why not just use toggle ? create macro, in advanced settings, “insert new key event” add your key you use probably 1, then action trigger set to “toggle”, action repeat set to “repeat constantly”, repeat delay set to “constant” then set the MS.
You can then click the macro button, when you want to run it, then hit it again to turn it off. I used G2 key on my K95 easy to hit with ring finger and always at that length.