Success, more or less.

After some fiddling, I got it running, pretty much.  Here are some 
notes, in case they might be of any use.  I used Xvesa.

The default mode, "0x0012: 640x480x4 0x0114: 800x600x16 TrueColor 
[5:6:5:0]Planar" did not work -- got a black screen.
I have an i810 which I use in 16 bit depth for XFree86,
so I tried all the 16 bit modes which -listmodes offered.  They all 
worked, with "0x0114: 800x600x16 TrueColor [5:6:5:0]" the highest
resolution.

Fdclock worked fine.  The doctored xterm worked, though I didn't notice 
any transparency.  Do you have to ask for it specially?  Xcompmgr
worked, though it wouldn't return when I called it in xterm, and
C-c. C-z had no effect.  But it was ok when I called it with "xterm&",
though I got an error message "error 134 request 137 minor 10", which, 
looking through the mail archive, I see others have encountered.

My console window was gone after I exited with C-Alt-backspace.  I had 
to reboot.  I used the option "-force-text", but that didn't help.

This is a lot of fun.  Thanks.

Greg