[xorg-server-1.9.2.902] How to set "EmulateWheelButton" with no hal?

[walt]

Hi xorg list, and Happy Holidays to you all.

I just updated xorg-server from 1.7.x to 1.9.2.902.  Everything works
as expected except for my unusual mouse, which has many buttons but no
wheel.

Until now I've been using a hal fdi file to set EmulateWheelButton to 8,
but now hal is gone, so what to do instead?

I have no InputDevice sections in xorg.conf because I've been using evdev
and my custom hal fdi file to configure the mouse (successfully).

Now I see that xorg is using udev instead of hal to detect the mouse, but
somebody is setting EmulateWheelButton to 4.  Is this now a default value
specified in xorg-server-1.9.x?

I'd like to get the Big Picture so I can configure the mouse using the
"right" tool for xorg-1.9.x.

Any clues accepted with gratitude and wishes for good holiday cheer :)