First off, people who bump threads are awesome!

Second, I wouldn't recommend just "replacing" a few of the system files, such as ntoskrnl.exe, with Win2k copies; your system may not boot at all if you do that.
I personally don't think it's possible, because it appeas to me that the system is no longer "keeping track," if you will, of the loading progress as it did with Win2k. I think this may be one of those things you have to either put up with, or teach yourself how to gain access to the XP source code, learn whatever coding language it's written in*, and re-write it yourself.
* this passage probably shows just how much I don't know about coding.