Refer to Apache and SSL Certificates for conceptual references.
The tool for working with SSL Certificates on IHS is called IKEYMAN.
Verify GSKit Version
Most current installs should be fine. However, you should still ensure that the GSKit packaged with IHS can start and is the minimal version for 2048 certificates.
To start GSKit regardless of the environment you must specify a JAVAHOME which points to a version of Java with JCE. IBM actually packages the right version of java for you. On Windows, go the command line and issue the following commands,
E:\ cd opt\IBMIHS\gsk7\bin set JAVA_HOME=E:\opt\IBMIHS\java\jre gsk7ikm.exe
Which should launch GSKit (IBM Key Management program). Click Help and then About iKeyman and confirm the version to be higher than 7.0.3.18.
Generate CSR
..
Import Private Key
...
References