Are you sure of the wisdom of this? I mean tyre manufacturers spend millions on R&D developing a tyre, and if it could be improved with an extra groove here or there, they'd do it. It would cost them nothing and improve the tyre.
I can see how more grooves could adversely affect the temeprature characteristics of a tyre for kick-off.
It would be in the mould at manufacture. I have no real understanding of tyre design, so I won't pretend I do, but I am a development engineer, so i have healthy resepct for those that do. Tyres are not just "Black & Round". These people are not fools, and to mess with their design is saying they are. Tyres are safety critcal. Someone is a fool here. Is it me , you or the tyre designers. Before you carry on, be sure the fool is me.
Now this is not a service we see here in the UK, but tyre design is a very complex subject, a black art, so a guy in a shed with a hobby knife or even a 'service' offered to random tyres should set you thinking...
Now, if you're going to do it, do it properly.
Winter tyres...