Animated GIF Automation in Photoshop

Need to automate the process of creating an animated GIF in Adobe Photoshop using Apple Automator. The automator will have to grab four (4) pictures from a pre-determined folder on the computer, bring them into the Photoshop program, add a PNG overlay over each photo (this can potentially be one PNG over all OR a different PNG for each image), place the photos on a Photoshop timeline, make the photos last 1/2 second each one behind the other in a sequence in the photoshop timeline, and then export as Animated GIF and save to a different folder.