http://www.truecrypt.org/docs/?s=command-line-usage
« sm or system: Without pre-boot authentication, mount a partition that is within the key scope of system encryption (for example, a partition located on the encrypted system drive of another operating system that is not running). Useful e.g. for backup or repair operations.
Note: If you supply a password as a parameter of /p, make sure that the password has been typed using the standard US keyboard layout (in contrast, the GUI ensures this automatically). This is required due to the fact that the password needs to be typed in the pre-boot environment (before Windows starts) where non-US Windows keyboard layouts are not available. »
Donc non, il n’y a que le QWERTY US de disponible pour l’authentification au moment du pre-boot.