To add/change icons, open EmelFM and click on the "H" in the upper left hand corner to show hidden files.
In your /home/dsl directory you will see a folder called .xtdesktop. When you open you will see your icons.
The .png/.gif files will be the icon image. The associated .ink file will contain the information that activates the icon. Bring up this file in your favorite editor and see how to create/change icons. It is very self explanatory. The "X" and "Y" entries determine the desktop location of your icon (in pixels).
If you add/change icon info you need to restart the WM to see the changes. It is a menu option in DSL. Just go Window Manager >> Restart.
(Thanks to Clivesay)