What does "booting progress" mean? The VM is running some code, but the VM has no idea what code is running now or might run next - except of course that the GAs could potentially be detected going active near the end of a typical guest boot.
So you can detect 0%, and 100%, but nothing in between - so I doubt that would be much of a "progress" indicator.
The VM is independant - think of it as another PC which has a shared network connection. Obviously you can poll some network API until you get a response, but I can't think of much else you can do.