To install DB2 on kristine, I had to hack at IBM's stupid install script
because it insisted on using the 1.3.1 version of java it had on its
install CD which didn't work, rather than the perfectly good version I
had installed.

First, to install IBM's Java 1.4.1,
  cd /afs/d/software/base/linux/Redhat.Enterprise.Linux.AS-3/RedHat/RPMS
(or it's on the last/ninth CD of the Red Hat AS distribution)
  rpm -Uvh IBMJava2*rpm    (this picks up IBMJava2-JRE-1.4.1-8.i386.rpm
                                      and IBMJava2-SDK-1.4.1-9.i386.rpm)

Then copy over the DB2 install CD over to /tmp,
  mkdir /tmp/db2.Install.CD
  cp -p /mnt/cdrom/db2setup .
  cp -pR /mnt/cdrom/db2 .

Then hack at the /tmp/db2.Install.CD/db2/linux/install/db2jinst script,
changing these 2 lines,
      Line  69 from JAVA_PATH=""
                 to JAVA_PATH="/opt/IBMJava2-141/jre/bin/"
  and Line 116 from JAVA_PATH="$INST_ROOT/java/jre/bin"
                 to JAVA_PATH="/opt/IBMJava2-141/jre/bin"

Then /tmp/db2.Install.CD/db2setup runs ok.