Changing sampled brush attributes

Hi,

Has any one been able to figure out how to change brush attributes trough scripting for other brushes than round without reseting the brush to round?

This is the latest info I have found about the issue: Change brush diameter - JSX script

According to this it is not possible. Is this still the case?

I have found that you can change the size without reseting the brush to round by setting "masterDiameter" instead of "diameter", but I haven't been able to figure out rest of the attributes, e.g. "masterHardness" does not work. I have no idea why "masterDiameter" works, because there is no field in the "currentToolOptions" for that.

Thanks!