GA Linear Equity Custom Fitness

Has anyone figured out how to write a custom fitness function that targets the most linear equity curve?

It would be easy to do a Least Squares Linear Regression if the fitness calculation had access to individual trade profit and loss. Is this possible?

Are there any non-published java script variables available to the fitness function?

Have a look at http://forum.tssupport.com/viewtopic.php?t=6828 it gives pretty linear equity curves.