What's the proper way to add a local file dependence to dub?

[Marc]

then copy it to sources folder?

let's say I have a small library folder at C:\mylibrary\D where I 
want to use dir.d from it. How do I add that file dependence to 
dub? But I do not want to that file be passed directly to dmd, I 
want to that file be copied to application's source folder (so 
it's easy to distribuite, with the dependences together as 
possible) then compiled. So, what I want to some extension is dub 
work with loca files.
Is this possible to do solely with dub? I know I can easily write 
a script to run before dub which copies the dependence files from 
C:\mylibrary to application's source but I'm looking for a more 
elegant
  approach as possible; I'm afraid of rewriting a makefile-like 
soon (I find cmake/make/makefiles just ugly).