I think it comes down to UPDATE_IMPORTS_XX in uimports.cpp. Unfortunately, I do not know enough of process structure to guess what you would need to do with this for it to work with wide LPCWSTRs.

In my case I currently just copy the DLL to the target directory if needed, though have also considered using subst.

use LPCSTR is because createwth.cpp use IAT to inject your dlls to destination process， so the imported dll name items must be ANSI version string，so it is not a problem.