ok, here at first the "dirty" (because we copy all files first, and so will use the double hddspace) manual way:
open a terminal, and change into the directory, you saved the images into.
create a workingdirectory there
become root
mount the isos something like this:
mount SUSE-10.0-CD-OSS-i386-RC1-CD1.iso CD1 -o loop
mount SUSE-10.0-CD-OSS-i386-RC1-CD2.iso CD2 -o loop
mount SUSE-10.0-CD-OSS-i386-RC1-CD3.iso CD3 -o loop
mount SUSE-10.0-CD-OSS-i386-RC1-CD4.iso CD4 -o loop
mount SUSE-10.0-CD-OSS-i386-RC1-CD5.iso CD5 -o loop
change into each mounted images directories ("CD1", "CD2" and so on), and copy everything from there into the workingdirectory, you created above.
while copying, you will be asked several times something about what to do with "MD5SUMS", "directory.yast" and some other files, and have the choice between skip, abort. --> skip
only the directory "suse" must be "overwritten", meaning, the files from the cds will be written into the already existing directory "suse".
then unmount
umount CD1 CD2 CD3 CD4 CD5
and
remove the loopdirectories
rm -v -r CD1 CD2 CD3 CD4 CD5
change into the working directory, where all the files are in now, an enter this:
mkisofs -v -r -J -b boot/loader/isolinux.bin -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o SUSE-10.0-CD-OSS-i386-RC1.iso .
make sure, not to forget the lonesome dot at the end of the line above.
about fifteen minutes later or so, you should have a brand new, bootable dvd-iso, about 3gigs large, called "SUSE-10.0-CD-OSS-i386-RC1.iso" in your working directory, you now can burn onto disk.
the other way is a script, but i have to rebuild it for the RC1. - stay tuned, it might take some time...

cu