Did you already try adding the MeshCentral agent through the Arduino sketch? https://software.intel.com/en-us/blogs/2013/10/18/meshcentralcom-now-with-intel-galileo-support.
You can check the instructions in the link above. It’s been tested using the SPI flash image, so I’m not sure if it’s going to work with the SD card image but you can give it a try.
Here’s another related video http://www.intel.com/content/www/us/en/embedded/products/galileo/galileo-09-meshcentral-video.html.