In other launch configurations (Java etc.), it's possible to add variables, like current_date or file_prompt (I can't enter the required dollar sign and curly brackets in this editor). This seems to work for Environment variables, but not for the parameters. This is a pity, because it's a very powerful feature in Eclipse.
I don't know Eclipse from a plugin developers perspective, but if this is easy to integrate, it would be a great feature!
Thanks for your great plugin, I really love it!