How to change external disk's FileVault 2 encryption password?

I currently have Mac OS X Lion FileVault 2 encryption enabled on my laptop's internal drive, but this question is regarding external USB drives:

I just recently used "Disk Utility" to format an external USB drive to the "Mac OS Extended (Journaled, Encrypted)" format. I then followed the prompt and assigned a password (say... "ABC" for example).

My question is: Is is possible for me to later change that external USB drive's encryption password of "ABC" to a different password after-the-fact?

Any help on this would be greatly appreciated. Thanks