How to boot from any image inside boot.wim

It appears that you slightly misunderstood (if I understood you correctly) the concept of the thread. From my point of view it looks like you're trying to patch the wim file. What you want to do is probably (since you posted in this thread) integrate all images into the same wim, and patch the windows bootloader instead. That's the whole reason why I've prepared a severely hacked bootmgr to make this possibly. If you have several different wims and want to keep it like that, then you don't need to bother with any patching as it can all be configured in the bcd store by MS's own tool bcdedit.exe.

Joakim