This works perfectly for me. Taken from a Desire HD:
ro.build.description=2.36.405.8 CL47853 release-keys
ro.build.fingerprint=htc_wwe/htc_ace/ace:2.3.3/GRI40/47853:user/release-keys
You'll need to toggle back for some HC apps though. Keep a copy of each version on your SD card and use the one you want. Reboot needed.
Try it and see if it works for you, keep a backup of original though, just in case
What does this "fingerprint" thing do? I keep seeing it here and there under this thread.