As of 0.9.4, when adding a symbolic link Mercurial keeps track of the link itself, and not the file or directories it points to. However, there are cases when it is desirabl
Under linux you can use
mount --bind sourcepath targetpath
instead of symbolic links and mercurial will treat target as usual directory (tested on openSUSE 11.2 with Mercurial 1.3.1, and on RHEL6).
The alternative syntax, amenable for inclusion in /etc/fstab, is
mount -o bind sourcepath targetpath
The fstab entry is, then
sourcepath targetpath none defaults,bind 0 0