You can use REG.EXE utility to create the registry entry you want. If you want to automate adding this entry as a part of the build process, you will have to create a component with the FBA Generic Command to call REG.EXE call.
I am going to move this post to the XPE/WES2009 forum as this one is for POSReady.
Sean Liming - Book Author: Starter Guide Windows 10 IoT Enterprise - www.annabooks.com / www.seanliming.com