Changing language on 580i: have i got it right

[SeaMonkey]

Ok. I am fairly certain that the phone is CID53(it is not infact my phone but my girlfriends so i cant check ATM)

So i just have to flash the FS and then the custpack?

Is there a specific custpack for each version of the FS or are they universial?

First of all connect your phone with XS++ and post log here(just check CID).
Custpack don't depend on CID but depend on FS (if FS is EUROPE 1 , than look for custpack
EUROPE 1 ).Like others said be carefully with MAIN - FS MUST be same version