Well, the answer is simple; unless you are on the console, then you can't. That is, you must be on DISPLAY ":0.0".
If your sys admin is denying you access, or it's a VM and you're not allowed console access, then you're also stuck.
The only other solution is to use the response files provided in the install directory of the installation media.
Customise the response file and then run the install.sh in silent mode.
There is a very helpful IBM help page on how to do all of this here: http://publib.boulder.ibm.com/infocenter/wasinfo/v6r1/topic/com.ibm.websphere.base.doc/info/aes/ae/tins_runSilent.html
ps. It presents a more systematic, repeatable approach to installing an environment if you use response files. No mistakes, same every time.
What's more, you can also silently install the "UpdateInstaller" and also the FixPacks.