Trackball drag button

[Alice Corbin]

I have a Logitech trackball with a fourth button.  In xfree86 4.3.0,  I
could set this button as a lock by adding these lines to the InputDevice
section of my X configuration file:

	Option	    "Protocol" "MouseManPlusPS/2"

        # Tells X about the 4th button (the red one).
	Option	    "Buttons" "4"

        # Sets the 4th button as a lock for button #1.
	Option	    "DragLockButtons" "4 1"

The first click of the button would be reported as a press of button 1
while the next would be the release.  (This allows me to drag objects
around on the window, which would otherwise be awkward with a trackball.)

I now have a new box with xorg-6.7.0 installed.  I tried adding these
lines to my xorg.conf, but didn't get the expected results.  Now a click
of the fourth button is reported (by xev) as a press and release of
button 2.  And when I read the man page for xorg, I find that there
is no description for the DragLock option (or for the Buttons option, 
or any of the emulateWheel options.)

Is there anything I can do to get the drag functionality in xorg?

Thanks,
Ali