Drop-in plugin for existing games?

[ThreeDeeJay]

Any chance steering wheel + FFB could be added to existing games by compiling into a DLL or something we can drop into the game folder or like an external injector tool? Or does it specifically the developers to add it to the project file and recompile?
If so, are there any plugins that do what I describe, besides stuff like DirectInput to XInput wrappers?