(updated on May 9 2021 with fixed links, etc.)
As a follow-up to a discussion on the OmegaT list*, I put my OmegaT launcher applescript on github:
https://github.com/brandelune/OmegaT-things/blob/master/%3EOmegaT.applescript
I'll write a more detailed post about that one later but it should be useable as is.
To test it, open it with Script Editor, select a valid OmegaT project in Finder, go back to Script Editor and click on Run (▶︎) or hit Cmd+R. You should see a dialog with 3 buttons and "Open Project" is selected ("Create Project" won't create a project for you because it calls code that I have not yet cleaned up, so you'll have to manually create a project, select it and then launch this script).
Clicking on it should launch Terminal, and from there OmegaT with a default command that looks like this by default:
java -Xdock:name=OmegaT -jar '/path/to/OmegaT.jar' '/path/to/project/' --no-team
Feel free to fiddle with the script and once you're satisfied with it, use File > Export and select "Application" as the file format. Then you can use it as a normal application to call it from Spotlight, etc.
There are plenty of TODOs in the file. I'm planning to slowly fill them with working code. If you have ideas, don't hesitate to make suggestions.
* After Didier Briel left the OmegaT project a few days ago, he asked me to take the role of "twitter community manager", and so I'm back into the OmegaT Project, after an 18 months lapse. Aaron Madlon-Kay is the new project manager. Don't hesitate to follow @OmegaTOfficial on Twitter if you don't already.