if you look in your startup folder (windows) you should find the shortcut to bitcoin client. Add the command line to generate coins to the end of the command and It'll always run and generate.
And what would that magical command line option be, exactly? There's no help file included with the program that documents this. I shouldn't have to do that anyway. Options selected in the program should be persistent between sessions. Or at least have a checkbox option that makes it so.