Rename the existing asantto asant.bak.
Copy the asant.template file in as_install/lib/install/templates/ee for SE or EE version to the as_install/bin/ directory and rename the asant file.
Edit the newly copied as_install/bin/asant file, replacing the %CONFIG_HOME% token with as_install/config value.
If any manual changes were made to the original asant.bak file, merge them into the new asant file.