How to control build of plugin from game project?

Hi,

I have a plugin and I need to give my users the option of building it with or without the vehicle engine-plugin.

I would like to allow the user to specify this setting within the project and not require a re-generation of the project files each time it is changed.

Is this possible? Allowing the project to setup definitions for an included plugin seems like a basic feature but I can’t find any info anywhere.

Thanks!