How do I use AFP with Back To My Mac?
You can find your Back To My Mac hostname by doing this:

% dns-sd -E
Looking for recommended registration domains:
DATE: ---Fri 15 Nov 2013---
12:00:39.211  ...STARTING...
Timestamp     Recommended Registration domain
12:00:39.212  Added     (More)               local
12:00:39.212  Added                          icloud.com
                                             - &gt; btmm
                                             - - &gt; members
                                             - - - &gt; 1234567


Using that you can derive the hostname as computer_name.1234567.members.btmm.icloud.com. Now use Finder's "Connect To Server..." command and enter afp://computer_name.1234567..members.btmm.icloud.com in the dialog box. It works! If your computer name has a space in it, replace it with a hyphen. The hostname should be all lower-case, so if your computer name is "My Mac" use my-mac.1234567.members.btmm.icloud.com.

(If your mac is running ssh, you can ssh to it as well, which opens a whole world of secure-tunnelling possibility!)