Normally, you engage an encryption program like TrueCrypt or ScramDisk, and you type in 'one' password or passphrase.
This proposes what might be termed a 'shell program' or 'front end', that sets up either one of two things;
1) that two or more copies of TrueCrypt, ScramDisk, or whatever, open side by side in 'parallel',
2) that two or more copies of TrueCrypt, ScramDisk, or whatever, open one after another in 'series'.
Thus, you start 'shell', and it automatically opens one copy of TrueCrypt, and you type in a passphrase.
TrueCrypt, operating in 'shell mode', receives the first password, unlocks, and reports back to 'shell'.
'Shell' thereupon opens number 2 copy of TrueCrypt, and you enter a second password.
TrueCrypt #2 unlocks, and reports back to 'shell'.
'Shell' confirms sequential entry of passwords, and unlocks.
The above is a clumsily worded description.
The idea is, you combine multiple instances of TrueCrypt, ScramDisk, or whatever, into a Multi-encryption shell-unit, unifying them into something that basically requires multiple passwords to unlock.
Thus, complexity is compounded, but unlocking is simplified by x-units of passwords entered either in parallel or series mode.