Photoshop :: Actions And Save For Web

I use the "Optimize to file size" feature in the Save For Web Panel constantly. I am planning on doing a large amount of conversions in the near future (by which I mean resaving .jpegs at a certain dimension and resolution. As far as the dimension and resolution go, there is no difficulty creating an action to do that. But the icing on the cake for me is have them all processed through Save for Web at a certain file size (for the sake of argument, say 500K). Yes, I know that the resulting images will vary in quality (obviously) because the end result will very much depend on their file size to begin with but that is not an issue for me for my purposes.
 
Save for Web has various presets and allows you to save presets; however, it does not allow you to save the Optimize to file size as a preset. When I try to record an action, and go to the Save for Web, use the Optimize etcetera, the action created lists the quality of the image I process to record the action. So, for example, if my image is less than 500K, the quality recorded in the action is 100. If my image exceeds 500K, the quality might be 86 and that is what the action records. For whatever reason, what is recorded is the quality rather than the 500K. I am not sure if this is being written clearly enough to explain. I want every image to end up being 500K regardless of what the final quality is (quality being the difference between the original image and the image as saved by Save for Web). But actions are saving the attribute of quality rather than file size.