#0.)  Burn with cdrecord (which is better than cdrw, because it has the driveropts=burnfree option which protects you from buffer underruns) :
cdrecord -v -eject driveropts=burnfree dev=7,0,0 /mnt/07/CD/EXPORT_RC0/Natamar_0.4__b96_sparc_cdrom.iso

#1.) just type "boot cdrom" at the ok-prompt

#2.) Be patient, relax, drink some coffee and enjoy (boot can take up to ten minutes on old boxes, because miniroot is still wayy too big (256MB),
     because its content is not yet fiocompress shrinked) 
#3.) Please tell other users about it, maybe in your blog. Merci.


Hardware Requirements:

Any sun4u or sun4v box (except those based on UltraSPARC-I at this time) with at least 512MB mem should be able to boot this. In case you have one of the Xorg-supported 
frame buffer <-- vs. --> pci bridge combinations it will boot you into Xorg7.2 running icewm, otherwise you can still use the text console. UltraSPARC-I support may be 
revived in an upcoming release. 
In case the boot fails chances are that your OBP firmware is not new enough to properly work with newboot. I successfully tested this on U10, U30, U60, Blade100,
Blade 150, Blade 1000, Blade 2000, Fire 280R and SPARCle500SX, while it does not boot on my U5 (which uses the same system board like the U10, only diff. is the older OBP).