I can pretty much customize Moksha themes and icons to my liking with one exception - some of the icons in the shelf.
As you can see I was able to change the icons in the ibar (bottom middle). Also by going to the themes>Advanced>Theme Categories I can change the clock icon to the Radiance theme even though on a shelve that is the MokshaSeven theme. Moksha will let you do this for almost every Gadgets the limitation being you get the icon the theme provides - like it or not.
The problem I am running into is the the network configuration icon is barely visible (lower right just to the left of the power button). To make it visible I can change the theme for the systemtrey but then the back ground color clashes with the shelf and looks bad. And anyway I really don't like the icon itself. How can I define a path to the icon of my choosing (/home/user/.icons/icon.png) for gadgets like network manager, clipboard, notification etc. gadgets not found in the ibar?
Network Manager icon is related to icon set installed in /usr/share/icons. You can change it under Application themes setting in Icons tab. I also added a check button in BL 5.1 moksha release to icon set bind with moksha theme automatically. As I maintain 13 themes, thus I created 13 icon sets with color theme matching. So if you want to break this feature, uncheck the option "match icons if possible" and select another icon set.