CCleaner only takes around 2 minutes at the MOST to completely clean off everything anyway. Add a shortcut of CCleaner to Windows QuickLaunch if you are finding it annoying going to it file path each time. Surely even if you do use the logoff.cmd file, you are going to have to manually click scan, I haven't found any option in my version to do with "Run Scan when programme starts".
A script or option for doing what you are after is useful, sure, but if you want to delete all your cookies and such when you log off, an even easier option would be to select the option in whatever browser you are using to "Clear All private data when browser closes". Ie7 and FireFox have these options, although I am un sure of other browsers.