How do I lock my mac without the screen going dark or going to the screensaver? When I used Alfred's Lock command my mac locks and shows a screen with a password prompt. I want to know if I can do this on machines that don't have Alfred installed. Is there a way to do by perhaps creating an automator service?
You can create an Automator workflow with a Run Shell Script action containing:

/System/Library/CoreServices/Menu\ Extras/User.menu/Contents/Resources/CGSession -suspend