Backup to DVD-R

[Chris Rodgers]

Hi,

I would like to backup all the files on my FreeBSD system to DVD-R. 
Unfortunately, there isn't enough spare disk space to create a 4GB .iso 
first.

Does anyone know how I might:

tar up the contents of the disk to files < 2GB in size (the .iso file 
size limit)
and then burn these onto a DVD-R
all without creating temporary files?

I'd appreciate any thought on how to do this.

Otherwise, I have a USB 2 hard disk that I could use for scratch space. 
Will that work under FreeBSD 4.6-RELEASE?

As a final alternative, would that USB hard disk work under Freesbie? 
Would I be able to mount my existing hard disk slices?

Many thanks,

Chris Rodgers.