A community tool released earlier this year automates the process and even patches the executable to unlock the so-called "new" DX11 features (like higher shadow cache limits). Search for "RE3 DX11 Switcher GitHub" for the latest version.
A common myth is that DirectX 11 reduces visual quality. With the DX11 enhancements, that is no longer true. In fact, some players prefer the DX11 presentation because: resident evil 3 directx 11 new