Preview.app: have it read file again when filesystem mtime changes?

Is there a way to force Preview.app to automatically update the window when the mtime on the file changes? Maybe some AppleScript? I'm finding I need to click focus Preview.app window in order for an update to the file to appear. I found a similar, yet different question on this. The use case is editing Tex/Latex files where a PDF is generated. I was to automatically view the changes in Preview.app. Right now, I see the only alternatives are the Skim app or using X-Windows, Mac Ports with the gv --watch file.ps app to monitor a postscript document. Another alternative is to use a third party application that causes focus when mouse hovers the window, however this requires moving the mouse as well, so not a great solution.