Creating a circle phaser from the commandline

I'm trying to get a circle chaser from the commandline. I've seen previous posts that state the 'Form' buttons in the phaser editor are just shortcuts for Accel/Decel/etc. values, but I'm struggling. If I set everything the same as the circle form button, the phaser is still just a line. The only difference is that the Accel/Decel fields in the phaser editor have a P in front of the numeric values, as opposed to an F which I get when I press the circle form button. However, I cannot seem to change this. I've a sneaking suspicion that this is the issue. Having looked at the XML of the predefined phasers library, there seems to be an AccelSplineType/DecelSplineType property, that is set to "Free" in the predefined circle phasers. Maybe this is what the F in front of the Accel/Decel values is indicating? Anyway, does anybody have some insight here how to change the values in such a way that I get a circle phaser?