First, download the IBM Java SDK from http://www.ibm.com/developerworks/java/jdk/linux/download.html
Install java (by running ibm-java-sdk-7.1-0.0-x86_64-archive.bin as root) into /usr/lib/java/ibm-java-x86_64-71.
Change the alternatives links by running:
update-alternatives --install "/usr/bin/java" "java" "/usr/lib/java/ibm-java-x86_64-71/bin/java" 1 \
--slave "/usr/bin/keytool" "keytool" "/usr/lib/java/ibm-java-x86_64-71/jre/bin/keytool" \
--slave "/usr/bin/apt" "apt" "/usr/lib/java/ibm-java-x86_64-71/bin/apt" \
--slave "/usr/bin/unpack200" "unpack200" "/usr/lib/java/ibm-java-x86_64-71/bin/unpack200" \
--slave "/usr/bin/pack200" "pack200" "/usr/lib/java/ibm-java-x86_64-71/bin/pack200" \
--slave "/usr/bin/rmid" "rmid" "/usr/lib/java/ibm-java-x86_64-71/jre/bin/rmid" \
--slave "/usr/bin/rmiregistry" "rmiregistry" "/usr/lib/java/ibm-java-x86_64-71/jre/bin/rmiregistry" \
--slave "/usr/bin/tnameserv" "tnameserv" "/usr/lib/java/ibm-java-x86_64-71/jre/bin/tnameserv"
Check to see if the settings are complete
update-alternatives --set java /usr/lib/java/ibm-java-x86_64-71/bin/java
update-alternatives --display java
java -version
java version "1.7.0"
Java(TM) SE Runtime Environment (build pxa6470_27-20131115_04)
IBM J9 VM (build 2.7, JRE 1.7.0 Linux amd64-64 Compressed References 20131114_175264 (JIT enabled, AOT enabled)
J9VM - R27_Java727_GA_20131114_0833_B175264
JIT - tr.r13.java_20131113_50523
GC - R27_Java727_GA_20131114_0833_B175264_CMPRSS
J9CL - 20131114_175264)
JCL - 20131113_01 based on Oracle 7u45-b18
Now you can use IBM java!