On Linux box:

mount -o loop uberks-latest.iso /mnt
(where uberjs-latest.iso is a RedHat UberKS CD, which is basically just a RedHat bootable CD with some extras we made)

(copy the files to a working directory)
# mkdir /uberks
# cp -r /mnt/* /uberks

(i've been building everything on sun, and have not tried to make these images on linux)
add /uberks to /etc/exports
add your sun build host to /etc/hosts.allow

Assuming you already have a working UberJS cd in /MySolarisCD On the sun:

# mount yourlinuxbox:/uberks /mnt
# cp -r /mnt/* /MySolarisCD/s0

# cd /MySolarisCD
# mkisofs -R -d -L -l -sparc-boot sol9.s1,sol9.s2,sol9.s3,sol9.s4,sol9.s5 -o sol9linux.iso -b isolinux/isolinux.bin -c !isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table ./s0

Then burn the cd anywhere.