Ahh it feels awesome to have a customized Web Client!, I know this is possible with VCenter Web Client, but it was totally different for ESXi HTML5 Client.
The basics is install via link above, connect via FileZilla *ssh*, and copy over the new files (to the webroot), deleting the originals first.
https://www.youtube.com/watch?v=7MH7rDnId5Q
Background Image + VMWare Logo + Loading Gif
Home Page Tower Image (not changing Logo above follows you throughout App!)
Change overlay image AKA cloak on Powered off VM's
Change GIF when you refresh page
HUGE shout out to two websites for the GIF's!