I think you are confusing terms, but I'm not sure.
The bootloader shows the LGE logo. It's untouchable AFAIK.
The IHO logo is an RLE image shown at the time of pass-off from bootloader to init process. It is located in the ram-disk (see below)
The 1st bootanimation is a series of RLE or PNG images started by the init process pre-boot, if in charging mode, it shows a different series of images. These can be changed, but it requires either building from source, or extracting the ram-disk then swapping out the images then rebuilding the ram-disk.
The 2nd bootanimation is a zip file that contains series of PNG images in one or more folders with a desc.txt file that has simple details for the animation sequence. Much easier to change.
BACKside-IHO has the option to change the 2nd bootanimation. You find a bootanimation you like, and place the zip file on your sdcard, then use the bootanimation chooser in settings to select it.
Note- if a bootanimation you try doesn't work, you may need to resize the images to 320x480 and change the desc.txt accordingly. Another common error is the zip file is zipped up in another zip file, so open it up and be sure it only contains folders and the desc.txt file.
Google is your friend for finding bootanimations, here's a couple of links to get you started:
[Boot Animation] [12/04/11] A Huge Collection of Boots ~ Updated - xda-developers
[BOOT ANIMATION] The Droids - xda-developers
Boot Animation Index