I don't know what that link is that you posted but frankly it looks like a PITA. It also looks like it's from 2.1 and the location has changed since 2.2. So I'll share my (easier) way of doing things.
To begin with, the Boot Animation MUST be named VZW_bootanimation.zip and if you are using audio, it MUST be named VZW_Droid.mp3
1. Place those (zip and mp3) files into your Android-SDK/tools folder.
2. Turn off your phone and plug it into your computer. Boot into HBOOT (hold down volume and power buttons).
3. Mount your system.
2. Back on your PC - Go to your Android-SDK/tools folder.
3. With nothing selected, place your cursor inside the folder then hold down the Shift key and right click. Select