Not exactly sure what you are asking, however you can use the .msi package for the BigFix agent and push out via GPO. If you use the .msi that’s created via the installation generator, then the masthead file is already embedded, so you don’t need a separate .afxm file. You can further modify the .msi to add other settings if you need, use Orca or a similar tool.
Also read this thread: https://forum.bigfix.com/t/making-a-bigfix-msi/8224?u=gwyndafdavies