It's not going to be easy because DA expects to serve the web from home.
One possibility to try (I haven't tried it and I make no statements about whether it works or not) would be to create your /pub directory and move everything from your /home directory to your /pub directory, and then delete the /home directory and create a symbolic link: /home -> /pub.
I understand that may not be what you want, but since DirectAdmin is a closed-source compiled C++ program, I don't think it'll be possible to do it any other way.
Jeff