Yeah, that's what I was doing. I tried messing around with the conf file directly too, but I could not solve the mouse issue with 4:3 resolutions. I was getting a double mouse cursor, which apparently is a common issue if you pick "Stretched but keep Aspect Ratio" or any similar option, so I don't think it can be fixed. The closest I got was picking the highest resolution available in the game's launcher, and using the "Centered" option in dgVoodoo. Thankfully the image is not too small in my monitor, so that's how I'm gonna play it.
I'll attach the dll and conf files, and a small readme for anyone else who for some reason doesn't want to download dgVoodoo and do it manually, for both full screen stretched and centered 4:3