I've followed the procedure from the
www.ergon.ch site successfully for Solaris 8 02/02.
One key is that the "magic number" used in computing the padding size will vary between revs of the Solaris CD. You can find it using the 'disktype' utility he mentions.
For Solaris 8 02/02 it was 788480 (1 more than the sector count of partition1->partition1).
The commands I used for building the iso:
( cd news1; mkisofs -no-emul -r -b boot.img -c .catalog -o ../news1.img .)
PADDING=`ls -l news1.img | awk '{print 788480 -($5/512)}'`
dd if=p0firstBlocks > ./newsol8.iso
dd if=news1.img skip=64 >> ./newsol8.iso
dd if=/dev/zero count=${PADDING} >> ./newsol8.iso
dd if=s0 >> ./newsol8.iso
dd if=/dev/zero count=600 >> ./newsol8.iso