Well I installed the latest docbook-utils but they still only accept SGML_files as input. I only have XML as input. Well here's the awful and buggy script that I'll have to use ...

bash-2.05b$ cat xml2sgml.pl
#!/usr/bin/perl -w
use strict;
my $doctypePat = quotemeta ( '<!DOCTYPE article PUBLIC "-//OASIS//DTD 
+DocBook XML V4.1.2//EN"' );
my $fl;
 
$fl = <>;
 
print $fl if $fl !~ /^\<\?xml/;
 
while(<>) {
        if (/$doctypePat/) {
                print <<EOT;
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V4.2//EN" [
<!ENTITY nwalsh "Norman Walsh">
]>
EOT
                <>;
                next;
        }
        s/article/book/g;
        if ( /\<\/bookinfo>/ ) { print $_; print "<article>\n"; next; 
+}
        if ( /\<\/book>/ ) {  print "</article>\n"; print $_; next; }
        print $_;
}
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