I achieved this live tweaking of parameters using Nic's Plugin Manager, which allows you to run the game in the Simulator and then build your plugin/parameters file which is then hot reloaded live into the running game. Incudes a demo/example.
I was tweaking values in a Lua table - one click/press to see the changes in the game - but there's nothing stopping you integrating Excel or SQL in your workflow if you so wish.