Migrating Custom Dialplan to FreePBX Distro

Hello, All. This is my first post here.

I have installed FreePBX Distro from Schmooze that comes with CentOS 6.5, Asterisk 11 and FreePBX 2.11.
Installation was like a dream am just getting started with preparing the system for use with my current phone configuration.

I currently have about 30 polycom phones and some softphones (PhonerLite) registered with Asterisk 2.4.
Since I already have all the polycom phones configured, I would like to reuse the same settings and not have to edit the phones’ configuration files.

The first problem I have whilst configuring my first phone is this:
Each extension is configured with a four digit number, say, 2222 for example.
The polycom’s first line is 2222-1, the secretary line is 222-2, the softphone is 222-3 the intercom line is 2222-6. I also use the same number (such as 2222-1) for both the line’s username, secret and the password (I’m behind a fancy firewall with NAT, so I don’t have to worrry).
The dialplan knows what to do with the last digit of the extension.

Now, I don’t mind reconstructing everything to work differently than what I have. But how do I use settings I already have in the polycom configs?