Now i know how the method of the video works, and tryed myself
He was using the program "PSN Demo Installer" --->
http://www.ps3hax.net/showthread.php?t=13383
The program ask you for the path of the .pkg in your PC. The name of the folder where you are going to place in PS3, and the name for the content (TITLE)... this is where he changed the title text (not inside the .pkg as i thought)
Then the program creates 3 files (d0.pdb, d1.pdb, and f0.pdb)... the first two are almost similar... and the last one is empty
This 3 files + the .pkg must be placed inside dev_hdd0/vsh/task/********
*The asterisks are the name of the folder you gave to the program and you need to create, usually is 00000002 because there is always a 00000001 folder inside dev_hdd0/vsh/task/
After this, you must turn off the PS3... then turn on... and the bubble is there... the rest is the same that can be seen n the video
This .pdb format is explained here --->
http://www.ps3devwiki.com/wiki/Proje...base_%28PDB%29
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This is what i have (slightly different than in the video)

And in the video:

*pendiente = pending (in english)... so there was an 1% installed im not sure if this has importance, and i dont have this tiny grey icon at the right, and i have an error at the end of the TITLE text (this
002/ is something that i didnt added, i tryed 2 times, and the same error was there)
The thing is... the XMB is "mounting" the .pkg from "vsh/task" folder, using the .pdb files
There is no PARAM.SFO involved in the bubble or inside the .pdb files
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So it seems there is no way to generate the bubble (and this installation process) other than using "vsh/task" folder in cfw 3.55
But... as i said, after 4.00 this works different (and the bubble affects several contents), this video explains the changes from a user point of view
This functions of 4.00 was confusing me all this time
PS3 Firmware 4.00 Removes PSP Copy For Installed Titles - YouTube