For my x86 machine, the english version 6.1.7600.16385 of bootres.dll has an md5 of a03fed2c2a186eaa7dd43900cdcfa3ab.
Now the resigned bootres.dll with and without timestamp has an md5 of 3820345d5b28e1bf5ed163a380b92016 and 9a911e6d2b2fea2cac41ffdf59839d39 repsectively. And by definition, the MS signed certificate has been invalidated.
The most interesting thing was the fact that timestamping is not required.
Note that I did not change the animation itself (because I suck at that), I just invalidated the signature and resigned the file with a non-MS certificated. That said, it should obviously work to also change the animation before you resign with your test certificate.
For certain reasons regarding this certificate, I am unfortunately not able (or willing) to distribute such a resigned file. However, when I get this going with my own created test certificate (I suck at this too), I may provide more evidence.
Last note. The Microsoft blabla below the animation, is not contained within bootres.dll. If testsigning is off or the file is not signed with a valid certificate, then the static image (you can inject into kernel) is actiavted instead. For the purpose of booting with animation, the kernel does not have to be signed.
Very last note. My system is still x86 and so I cannot say about x64 (and patchguard).
Joakim