Keystone tool: click to place each corner point instead of dragging

I'd like an option in the four-point Keystone tool to set each corner point by simply clicking on the corner of an object, rather than dragging each of the default points into position. Working with large numbers of paintings/artwork this would be extremely helpful. For example: select the Keystone tool, click the four corners of the object with cursor, then click Apply as usual. Clicking on the corner of the object would move the closest keystone point to the exact point clicked on.