Same directory for the 4K and the Access 500/Branch. Below is valid for V6 R2, V7, V8. You can use it on V6 R1 if you can copy the firstinst-netw script onto the 4K.
cd /var/opt/firstinstall
./firstinst-netw.sh -w
It will rebuild the XML with the -w switch and tell you the filename it has created. Remember to use the platform linux, not the Assistant.