As mentioned in other threads, there are two GitHub sources for a solution to this specific problem:
Steps 1 and 2 to install the Chan-SCCP-B module from GitHub. Interesting new success with Chan-SCCP-B and SCCP-Manager (both from GitHub)
Once you do that, the phones will work in Skinny mode and be managed from the FreePBX GUI. It’s not EPM, and it only works with Skinny/SCCP phones, but it’s an option. There are a couple of gotcha’s in the install right now, but I think they’ve been addressed in recent weeks.
Short of that - you can try to manage it all by hand through your SIP settings.