If you have a (US) Pro S or First Edition, you can control the footwell lights independently in the custom Ambient Lighting settings:
If you don't have the custom settings (as on the base Pro model), I suspect you'll have to turn ambient lighting off completely, but I can't say for sure...
If you don't have the custom settings (as on the base Pro model), I suspect you'll have to turn ambient lighting off completely, but I can't say for sure...