The first boot splash on Imagio (the black htc logo) has to be flashed and your whitestone has to be hardspl'ed to change to a custom one. Its made up of the Main_splash.nb and Sub_Splash.nb.
http://forum.xda-developers.com/showthread.php?t=405118 is a thread about it.
Attached is the stock boot splash.nbh I made to return you to stock should you mess it up. You will want to use the custom_Ruu for whitestone I made that you can download in the shipped radios for whitestone thread to avoid a hard reset after flash.
The other animations are controlled by these reg keys:
Code:
[HKEY_LOCAL_MACHINE\Software\HTC\HTCAnimation]
"StartupGif"=""
[HKEY_LOCAL_MACHINE\SOFTWARE\HTC\Poweroff] ;shutdown animation on "0" is off
"PlayShutdownAnimation"=dword:00000001
[HKEY_LOCAL_MACHINE\Software\HTC\HTCAnimation]
"ShutDownGif"=""
[HKEY_LOCAL_MACHINE\Software\Microsoft\Splash Screen]
"MSBitmap"=""
[HKEY_LOCAL_MACHINE\Software\Microsoft\Splash Screen]
"CarrierBitmap"=""