I've tried Diskpart commands like "list""volume" (no it's not that at all), "disk" and "partition"; but it still don't work.
\Device\Harddiskvolume0 seems to not be used, since \Device\Harddiskvolume1 means the first Windows' partition (aka "System Reserved") and \Device\Harddiskvolume2 is for C:.
So the question is: How to list every \Device\Harddiskvolume in Windows' 7 installation disk (for BCD editing) ?