Powerpoint uses a browser rendering engine that is too old to support modern web standards, and therefore we cannot show your wall using PowerPoint directly within PowerPoint without heavy modifications. However, Microsoft makes a plugin called Web Viewer, which has the ability to embed a webpage into your PowerPoint slides using a newer browser rendering engine that supports modern web standards.
After downloading the Web Viewer and installing it, you can then copy the URL to your social wall, and paste it into the Web Viewer plugin to display the wall.