How to use Windows 8.1 USB Installation Media as DISM Source?

Is it possible to use a Windows installation USB drive as the source for DISM? The USB installer was created using Microsoft's Media Creation Tool.

This MS article states:

You can use a mounted Windows image from a WIM file as a source to restore optional features and repair a corrupted operating system.

The answer in this thread says to use the install.wim file on the installation media.

4.1 DISM /Online /Cleanup-Image /RestoreHealth /source:WIM:X:\Sources\Install.wim:1 /LimitAccess

But on a USB installation media, the file is called boot.wim, not install.wim.

I tried the syntax as in that thread:

DISM /Online /Cleanup-Image /RestoreHealth /Source:WIM:F:\sources\boot.wim /LimitAccess

and got

Error: 87 An error occurred while processing WIM:F:\sources\boot.wim. The specified path was not found.

This article states i can mount the .wim file, and point to the Windows directory inside it. That failed too:

DISM /Online /Cleanup-Image /RestoreHealth /Source:C:\bootwim\Windows /LimitAccess

gave:

Error: 0x800f081f The source files could not be found.

What am i doing wrong?

(Note, plz let me know if this is the wrong group for this question. I was told the only choices for Windows questions are ServerFault, and SuperUser. SuperUser is described as "for computer enthusiasts", and i think this question is beyond "computer enthusiast" level.)

I've never used Microsoft's Media Creation Tool before, so I am making some assumptions here. I do, however, work with OS imaging all the time using MDT, WDS, and SCCM (including the boot images those utilities create), so I am very familiar with the process and how Microsoft structures Windows install media in general.

That being said, there should be two .WIM files in the \Sources directory on the USB stick you have; boot.wim and install.wim. Boot.wim is the WinPE install image, and install.wim is the operating system's core files. This has been the source media structure for Windows since Windows Vista.

Check the sizes of the .wim files you have. Your boot.wim file should only be a couple hundred megabytes in size. Install.wim will be several gigs (3-4) in size. If you do not have an install.wim file in the \Sources directory on your USB stick, and your boot.wim files is only a couple hundred megs like it should be, then I would say that the USB stick is malformed somehow.

If your boot.wim file is very big (this is where my lack of knowledge on the MS Media Creation Tool would come into play), then the install.wim file you're looking for is probably inside it (although I've never seen install media created this way). If this is the case, then you will need to either mount the boot.wim file to a directory on your hard drive (also using DISM), or extract it using 7-Zip or a similar tool that understands .wim files.