I have used the method above, and do use it on my nook color. The developer is also responsive and I am sure could give help to making it work with the xoom. I believe it would just be a matter of getting the partitions correct.
With this solution you open a terminal prompt on the tablet, type
then it prompts for a password
creates an encrypted data partition, unmounts the current data partition and mounts the new encrypted one, then restarts the display. Think of it as a softboot.
Takes about 30 seconds, and when it comes up it is a completely different profile.
As it currently is coded, to get back to the default (boot) profile you just reboot. But I believe it could be changed to unmount and remount the main partition without having to do a hard reboot. But I haven't tried coding that yet.
I have 3 accounts on my nook, the default one it boots into (my daughters account), then two others one for my wife and one for me.
Works very well.