Just install the Linux client of your choice (runtime, admin, app dev, etc).
Make sure you have a 1.4.2 JVM installed.
You are probably confused because the server versions have different builds depending on the kernel version (2.4 vs 2.6). That difference to for the server to take advantage of 2.6 features. The client does not need any of this, so just one flavor.
HTH
Andy