I had to edit an L5K file in a text editor to change the controller and version.
The easiest way is to create a new ACD with an Emulate controller, export it to L5K, and export your own ACD to L5K, then copy the program parts from your L5K to the new L5K, save, and reimport.
Of course, you're going to have errors for any missing real I/O, because you can't match your real I/O to Emulate I/O. This is where if you have a I/O mapping routine, it's easy just to delete the routine and JSR in your Emulate ACD.