You can't really automate LR with AppleScript/Automator. The nearest you can get is triggering a Photoshop script (better JavaScript rather than AppleScript or VB) directly from Lightroom, but you'd have to write that a Lightroom plug-in using LR's Lua coding language and include lots of other code to watch for images output by Photoshop. So for practical purposes, the best way to do it is as I said earlier - launching a droplet via "edit with".