I have one guitar I don't care anything about and I used that method. I would take a little pocket screwdriver like techie types all have in their shirt pocket and slide it just in front of the nut. It worked, but there's nothing like the feel of sitting with your hand over the neck instead of under it and playing slide.

I wonder how much it would cost me to have a guitar maker to take the guts from a Variax and put them into a pedal steel? Not that I'd do it but what a cool concept! I played a friend's Variax and played some slide while changing from standard tuning to open D to open G to open E for testing reasons and it worked just fine. The advantage there is that you can edit those presets so if you want a 6 or a 13 chord you just tell the Variax to do that and it does it. Love those things. The James Tyler versions have far more reliable electronics that the original ones, which seemed to not handle humidity well and the guys I knew that had them all said that random strings would just stop responding. Not one of them ever played a gig without a backup guitar or two on stage.

But again, sitting over the guitar... Channeling by inner Alvino Ray! Slide guitar with a talk box!

Fun fact nobody cares about. He was born in California but grew up in Cleveland!