[H-GEN] VNC colours >8bpp

[The Fuzzy One]

I'm hoping one of you kind folk could answer a few questions :)

I've got an ET4000 card (not W32i, or anything fancy), and X does not
support high colour modes for it.  Conversely SVGAlib does support
true-colour for my card, hence I would like to run X through SVGAlib.

VNC permits an SVGAlib client to connect over loopback to a modified X
server that should permit me to run X.  The problem I'm encountering is
that the client and server seem to be blaming each other for the failure
to do more than 8bpp.

I have the following line in /etc/vnc.conf for server config:
$depth = "16"

The client gives me:
svncviewer: Connected to VNC server, using protocol version 3.3
svncviewer: VNC server default format:
8 bits per pixel.

while the server gives me:
rfbProcessClientProtocolVersion: client protocol version 3.3 (server 3.3)
Client Pixel Format:
8 bits per pixel.
Uses a colour map (not true colour).

Since neither takes the blame, it's been difficult trying to track down
exactly what's going wrong.  I'm fairly sure that SVGAlib is supporting
high-colour in zgv, however I have no evidence more definative than "The
F-Keys work" and "She looks pretty fine".

Has anyone done anything similar?