FreeBSD on USB drive for a MacBook Pro

[John Nielsen]

I'm looking for advice and/or pointers. I have an Intel-based MacBook Pro 
and I would like to use a USB thumb drive to be able to boot FreeBSD on 
it. Some questions:

1) Is this even possible? I've read that you _can_ boot Mac OS X from a 
USB hard drive on a new MacBook but I'm not sure if the same goes for 
non-Mac OSen or thumb drives.

2) What steps should I take to partition the thing? What boot code should 
I use and where should it live? I'm planning to do a manual installation 
in any event.

3) If I manage to get 1 and 2 sorted out, will I be able to boot the same 
thumb drive on a regular PC? Will any additional steps be necessary?

4) Just to be contrary, I'd also like to use GELI (if possible) for 
everything but /boot. Does needing an extra /boot partition change 
anything?

I'll be doing some experimenting, but if some things are already known 
(not) to work I'd like to start with as much info as possible.

Thanks,

JN