Adapted from http://digitalhacksblog.blogspot.com/2015/01/it-worked-for-me-winpe-bitlocker-and.html, updated for Windows 10

C:\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools>dism /mount-wim /wimfile:c:\winpe_amd64\media\sources\boot.wim /index:1 /mountdir:c:\winpe_amd64\mount

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Mounting image
[==========================100.0%==========================]
The operation completed successfully.


C:\winpe_amd64>dir "\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\WinPE-WMI.cab"
 Volume in drive C has no label.
 Volume Serial Number is 1C35-11BE

 Directory of C:\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs

07/16/2016  05:03 AM         6,166,228 WinPE-WMI.cab
               1 File(s)      6,166,228 bytes
               0 Dir(s)  29,428,953,088 bytes free

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\WinPE-WMI.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-WMI-Package~31bf3856ad364e35~amd64~~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\WinPE-FMAPI.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-FMAPI-Package~31bf3856ad364e35~amd64~~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\WinPE-SecureStartup.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-SecureStartup-Package~31bf3856ad364e35~amd64~~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\WinPE-EnhancedStorage.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-EnhancedStorage-Package~31bf3856ad364e35~amd64~~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\en-us\WinPE-WMI_en-us.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-WMI-Package~31bf3856ad364e35~amd64~en-US~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\WinPE-Scripting.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-Scripting-Package~31bf3856ad364e35~amd64~~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\en-us\WinPE-Scripting_en-us.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-Scripting-Package~31bf3856ad364e35~amd64~en-US~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>dism /image:C:\winpe_amd64\mount /add-package /packagepath:"\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Windows Preinstallation Environment\amd64\WinPE_OCs\en-us\WinPE-SecureStartup_en-us.cab"

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image Version: 10.0.14393.0

Processing 1 of 1 - Adding package WinPE-SecureStartup-Package~31bf3856ad364e35~amd64~en-US~10.0.14393.0
[==========================100.0%==========================]
The operation completed successfully.

C:\winpe_amd64>e:

C:\winpe_amd64>dism /unmount-Wim /mountdir:c:\winpe_amd64\mount /commit

Deployment Image Servicing and Management tool
Version: 10.0.14393.0

Image File : c:\winpe_amd64\media\sources\boot.wim
Image Index : 1
Saving image
[==========================100.0%==========================]
Unmounting image
[==========================100.0%==========================]
The operation completed successfully.


C:\winpe_amd64>MakeWinPEMedia /UFD C:\WinPE_amd64 e:
WARNING, ALL DATA ON DISK DRIVE e: WILL BE LOST!
Proceed with Format [Y,N]?Y
Formatting e:...

Setting the boot code on e:...

Copying files to e:...


Success


C:\winpe_amd64>
C:\winpe_amd64>