I found a great little utility that can enumerate through all the block devices, including your lvm, crypt, etc.
If you search for information on how to do LUKS encrypted home volumes, you're likely to get these big fluffy documents on how to do it. Well, if you're like me, you'd like to skip all that fluff, and get straight to the point. That's what I try to do here. If you like, you can completely ignore what I'm saying here, and just use the commands; it really isn't complex.
Keep in mind that this will only work for a maximum of 8 users per system. Anything more than that, and you will have to resort to either full disk encryption, or some other method of encrypting your /home files.
I would try this out on a 1G volume or something just for fooling around. Then once you've got that working, do it to your actual home directory. I use LVM with mine, but it could also be a raw partition if you prefer that. If it is a removable drive, I HIGHLY recommend using LVM, because you will be able to reference it by lvm "name". Using a partition for external drives becomes difficult, because you cannot name an encrypted volume.