Alright the I will explain the theory as I do not know the files you want to use. The methods used will also be similar to those for the other request in this thread (aside from the potential size change).
You need not pull apart the entire rom for this, quite in fact I used NDSTS:
http://www.no-intro.org/tools.htm
The location of the sound file is the "data\rom\ds" directory (note for ndstool/dslazy/dsbuff users the game has a directory called data so for you it will be the "data\data\rom\ds" directory.
You could do it in situ and either account for the location of set your editor to the start of the file (FBEC00 hex) but extracting is easy enough.
Initial shot of editor
This means little however so we need to find the files you want. Crystaltile2 time:
Now for instance if I wanted it to play "001-BGM_TITLE.SSEQ" instead of "002-BGM_NEBULA.SSEQ" I could find the location of the 002-BGM_NEBULA.SSEQ (in this case 71e0 hex in the sdat file or FC4300 hex in the rom).
Back to the editor. I need the string dealing with "002-BGM_NEBULA.SSEQ"
The files are the second and third entry but in reality you would find them by matching name to location (the ASCII name list is usually present and if you search for "FAT" in ASCII you will get the location list.
In this case using the info from crystaltile 2 you can see what needs to be changed
The yellow highlight is the search for "FAT", the red letters are the location info and the black and yellow text is the file length.
You want the "001-BGM_TITLE.SSEQ" instead of "002-BGM_NEBULA.SSEQ" so the third entry (second highlighted) will need to match the second entry (first highlighted) or:
Save the file and no change in length should have happened so you can just import it again with NDSTS.
This is all that was done for the tetris sound hacks, the castlevania POR stability hack and the pokemon sound hacks.
