I've cracked this - the problem mainly lay with openssh which I'll describe in:
http://groups.google.com/group/comp.security.ssh/browse_thread/thread/ce30a1d9889dc2e2#From a syslog-ng point of view the config was even simpler than I expected. I didn't need to define a new source within the chroot jail. All I have is (what I had before):
source syslog {
internal();
sun-streams("/dev/log" door("/var/run/syslog_door"));
udp(ip(0.0.0.0) port(514));
};
The magic trick is that on Solaris 10, you need /dev/conslog in the chroot jail - and that is all.
So create the device by getting the major/minior numbers for conslog:
% ls -lL /dev/conslog
crw-rw-rw- 1 root sys 21, 0 Jun 5 14:36 /dev/conslog
And create the device file:
% mkdir /path/to/chrootjail/dev
% mknod /path/to/chrootjail/dev/conslog c 21 0
Need to alter perms on this as well. The SSH perms are quite odd - top level of the chroot jail must be owned by root and must be modes 750 or less.