It might be possible to control the speeds by just using different Z depths - the only reason to actually move the plains when scrolling would be to exagerate the parallax effect, which might be the desired look. When I did something similar, I used quite a narrow field, like for the main screen I used a 4096x1024 plain, then the layers would be every 100 units or so, and the size of each plain would increase by 10 percent. If that was stretched out, then it might give that effect, meaning no need to move the plains.
It does depend on the game, and how it's constructed - when I did this it was quite a straightforward demo, using a big image for a mask, and a big image for each layer. The thing about that noir, monochrome art style, is that as .PNG textures those images will take up practically no disk space - my demo, with a mask, and 5 layers all at 4096x1024 weighed in at around 1mb, EXE included!.
Health, Ammo, and bacon and eggs!