KS: can I supply default values and allow the user to override them?

["Avner BenHanoch" <avner kinor com>]

I want to let the user configure some parameters (like network settings),
but supply him with default values for these parameters (like:
"network --bootproto=dhcp --device=eth0").
If the user type something then the system should use it, otherwise (let say
after 30 seconds) the system should use my default values.
The rest of the installation should remain silent!

Is this possible ?