I've found the solution for this one. For my Integral Technologies
Flashpoint 4Xl frame grabber with the S3 Savage IX graphics chip, the magic
incantation is to include the line
Option "sw_cursor"
in the device section of the /etc/X11/xorg.conf file, and put the line
Xcursor.core: true
in the user's .Xresource file.
In fact, there are several undocumented new X resource options for the latest
Xorg release for Xcursor:
Xcursor.core/XCURSOR_CORE bool
Whether to use core cursors exclusively, overriding any available
Render extension capability.
Xcursor.size/XCURSOR_SIZE int
Nominal size for cursors. Themed cursors can have multiple sizes
for each cursor, Xcursor picks the size closest to this size from
those available. If Xcursor adds SVG support, this size will be
used to scale the SVG objects.
Xft.dpi int
If Xcursor.size isn't set, then this value is used to compute the
nominal size = dpi * 16 / 72
Xcursor.theme/XCURSOR_THEME string
Name of theme. Xcursor uses the freedesktop.org icon theme
specification to locate cursor files; cursors live in one
of the icon directories in a cursors subdirectory. Xcursor
looks in the standard icon directories, along with
/usr/X11R6/lib/X11/icons. It also parses the index.theme
file to follow Inherits values. If no theme is set, Xcursor uses
'default'
Xcursor.dither/XCURSOR_DITHER threshold/median/ordered/diffuse
Dithering algorithm when creating core cursors. Xcursor transforms
an ARGB cursor into a two color cursor with one of these algorithms
(yes, only ordered and diffuse are really dithers). The default
is ordered, which is a 2x2 ordered dither.
Xcursor.theme_core/XCURSOR_THEME_CORE
If the server doesn't support ARGB cursors, this value controls
whether Xcursor goes ahead and themes core cursors using the core
cursor requests.
Reference:
http://www.cs.umn.edu/help/software/linux.php
http://handhelds.org/~mallum/downloadables/experimental/xcursor-notes.html
and, of course, the Xcursor source code.