It is not possible to add profiles. But you can customize the slow fast and relative profiles. You do this by installing profiles.txt in your ~/Library/Application Support/com.claudeheintzdesign.lxseries/lxconsole folder and then editing it. The format is very similar to what you suggest except that it uses equals instead of semicolon. Take a look at the the help for setup window->profiles tab.
Very helpful. Here I have uploaded a simple spreadsheet in case anyone wants to whip up something quick themselves.
As an example, this is a safety profile that will drive the aisle lights at a minimum of 20% and then fades linear up to 100%, but obviously the sky is the limit on what mathematical formulas one could build for their own fade curves .
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