right way to use the SFC options /offbootdir and /offwindir. Why they do not work as expected

Several times i try to repair w8pro using sfc /scannow in various manners in elevated cmd or from usb recovery console with different additional options, i always get stuck with unable to repair because no source files. It seems that /offbootdir=<path to my unpaked install.wim> does not work for sfc. Where do i place files that sfc could find them? I think about dll cache but i do not know how to it in w8

In Windows 8 use the new DISM command to fix file corruptions

DISM /Online /Cleanup-Image /RestoreHealth

When Windows detects corrupted files it will download them. You can also use the command offline and point to a WIM to get the data:

Dism /image:C:\ /Cleanup-Image /RestoreHealth /source:wim:D:\install.wim:2