To do this start Deployment Tools Command Line as Administrator.
In this instance I was creating a x64 boot.wim and the command to run for this was COPYPE.CMD amd64 c:\WINPE64\
Here are all the commands for the different architectures:
COPYPE.CMD x86 c:\WINPE86\
COPYPE.CMD amd64 c:\WINPE64\
COPYPE.CMD arm c:\WINPEARM\
Execute the command.
Once run, navigate to the c:\WINPE64\media\sources folder and copy the boot.wim to a share for use with SCCM.
In the SCCM console go to the Software Library workspace. Open Operating Systems>Boot Images. Right click and choose ‘Add Boot Image’.