s/^\#?\(xend-relocation-address ''\)/(xend-relocation-address '\${internal_ip}')/m or die;
s/^\#?\(xend-relocation-hosts-allow '[^']*'\)/(xend-relocation-hosts-allow '')/m or die;
+s/^\#?\(network-script '[^']*'\)/(network-script 'network-bridge')/m or die;
s/^\(dom0-min-mem [0-9]*\)/(dom0-min-mem 1536)/m or die;
+s/\$(\{XEN_CONFIG_DIR\})/$1/m or die;
print;