HOWTO write udf (on cd/dvd/hd wherever)

[scion+fbsdq at webrelay.net]

I see mount_udf(8), and I see many mentions of dvd+rw-tools, and growisofs.
Bud I don't see any mention of a method of writing a UDF?  Am I missing 
something?

Ultimately, I want to write UDF to a hard drive at the end of a USB so that
I can mount it elsewhere.

Clues? pointers? slaps in the face for not looking in the right place first?

Cheers!
-sam