OK, let's try breaking it down a bit.
Firstly, are you aware of the Skin Shortcuts Docs:
overrides.xml file? This file is where you define a lot of the behaviour of Skin Shortcuts - from how your management dialog works (additional controls, for example, or which shortcuts or widgets are available when clicking the associated controls), and provide defaults for your shortcuts that aren't defined in the .DATA.xml file - here's an
example overrides.xml file which, amongst other things, sets default widgets for various menu items and sets the gui control's 601, 602 and 603 to let the user select an additional property.
In terms of Skin Shortcuts Docs:
Managing widgets, there are various elements to getting these working. Firstly, you add a button with gui 312 to your management dialog - your users can now select a widget and the properties will be available in the built menu. Then you can set defaults (note that once the menu has been edited these won't be automatically applied - it's worth resetting the menu to default to see what effect your changes are having). After that you could choose to make additional widgets available. The final stage is actually displaying the widgets which is either done via Skin Shortcuts Docs:
Templates, or a pure skin-side solution. You still need to say where you are struggling with this.
In terms of Skin Shortcuts Docs:
Custom shortcut properties. If all you want to do is have a default shortcut have an additional property, then you can set a default for the menu item with that ID. You could additionally define a gui id to set the value within your overrides and then include a button with that id in your management dialog. Finally you then display the background based on that property, which is a pure skin-side element. Again, you still need to say where you are struggling with this.