Preparing textures to be exchanged by user

Hi,

we are trying to use the unreal engine to make a cool presentation. To make this presentation user friendly and save some time it would be nice if we could exchange some of the textures that hold the content by just overwriting files in the final, already packed project.
Is there a way to mark a texture as “mod-able” or something similar so that it is not packed and encrypted in the usual pak files?
Or maybe there is a way to insert some kind of dynamic link instead of a fixed file?

Any help would be much appreciated.