The Windows Volume Shadow Copy Service is currently supported only for partitions within the key scope of active system encryption (e.g. a system partition encrypted by TrueCrypt, or a non-system partition located on a system drive encrypted by TrueCrypt, mounted when the encrypted operating system is running). Note: For other types of volumes, the Volume Shadow Copy Service is not supported because the documentation for the necessary API is not available. (http://www.truecrypt.org/docs/?s=issues-and-limitations)
Я бы вместо альтернативы трукрипту искал альтернативу службе VSS.