There's another tool made by Dabore: DSIC (Dabore Sing It Customizer)
http://www.megaupload.com/?d=AN99IJHI
(I didn't mention in the guide due to I only use it for the final custom check, cause is very useful to see errors in paths)
It's another content.xml, editor, and it's in English
It has a good images conversor (.tex bmp, png, jpg, tif and more),
And there's the possibility to extract (.TEX to .JPG...) the Skins of the game, and after Replace... Really interesting
Basic (translated from EOL) Guide:
* Unpack and put dll's into to the program folder
* "File -> Open": browse to the folder where was extracted and modified the partition1 of the Game with Wiiscrubber
* Tables will be filled (at the moment game options can't be modified)
* Tables include all the content.xml. information, and Snapshots (.TEX) in Audio/video sheet .
* Images can be saved and modified (right click in the image). Be carefull with 'Replace', operation is done directly (no previous warning)
* More option "Utils->Add song" in four steps, to choose Artist, songs (one/more XML), vídeo, snapshot (image) and other. El "Album" es la primera carpeta dentro de "songs" (como HSM, por ejemplo) y "Folder" es la carpeta propia de la canción (como HSM_BF, por ejemplo)
* To end go to "File->Save" to generate the new content.xml
Source. EOL (http://www.elotrolado.net/hilo_estudio-proyecto-custom-sing-it_1146643_s90?hilit=partition+builder)