Openser, Asterisk and FreePBX combo

I’d like to implement a large deployment using openser as my registrar and proxy server and asterisk to implement all the features. I’d like to have these on two separate servers. There are plenty of documents on how to deploy openser and asterisk combo, but I haven’t found anything that allows you to use freepbx for the asterisk interface in this setup. Has anyone implemented such a deployment or know of where I can find documentation on how I can integrate Openser, asterisk and freepbx?

Thanks in advance.