Through the CLI, I would like to select the flurry screen saver set to activate in 15 minutes and show the clock.
Firstly, set your screensaver to Flurry in System Preferences and check the checkbox to show the clock.
Open up the terminal and type
In 15 minutes, the screensaver will activate with Flurry and show the clock.
The sleep 900 line controls the delay, so 900 is 15minutes in seconds (15*60).
You could add an alias for this command in your ~/.bash_profile so that you don't need to type this large command every time. eg if you wanted to have ss be the command then enter this into the ~/.bash_profile
alias ss='sleep 900;/System/Library/Frameworks/ScreenSaver.framework/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine&'
Hope this helps.
Unfortunately there isn't a general program to set arguments in the System Preferences so you will need to edit the plist files where the settings are stored.
The important file with the timeout and the module name and path is
Flurry has a plist file as well for it's settings, but I suppose you could set them or use the defaults if needed.