I wrote an entire installation process for the SCCP Wiki on GitHub. Search “FreePBX Chan-SCCP-B @GitHub” and you should get to the FreePBX installation instructions on about 1 click.
There is a GUI module for SCCP phones now that works with versions after FreePBX 1.8.
The GUI module includes custom softkey mapping - you can’t edit the ‘default’ list, but you can create as many as you want.
I had a little trouble when I installed the Manager over the weekend - there were a lot of “duplicate definitions” in an Include file that was getting added twice, but I think that might be fixed. If you run into trouble, let me know through a DM and I’ll walk you through the fix. There was also a change that I decided to make to the Makefile for the Chan-SCCP module, but that’s minor. Let me know through DM if you run into any problems. They aren’t Sangoma modules, but they’re not much harder to install than anything else in Linux.