http://www.snowcovered.com/Snowcovered2/DotNetNuke/Skins/GCM-Skin-Per-Role-410/id/6163

SkinPerRole dynamically changes the skin and container settings of your DNN portal based on user roles. Administrators can assign skin and container to a role. When user logs in, the entire portal is displayed with the skin and the container assigned to his or her role.

The SkinPerRole module can be deployed as standalone module or as a skin object. SkinPerRole will not interfere with the content of your site. It becomes automatically invisible to users that are not members of the Administrators role.

Is this close enough?

You probably have 2 ways: 1. Edit the DNN core code 2. Write your own code.

For #1, you would need to download source code and edit \Library\Components\Skins\Skin.vb. It looks like somewhere around line 160 on the file where it appears to be specifying the skin folder. ( Private Function LoadContainer()). You would need to create a new table called something like "UserSpecificSkin" with "ID", "UserroleID", and "SkinName". and you write a code - If(UserSpecific Skin is set) then{overwirte the skin folder please}.

Hint: You do know the administrator role can have their own skin, right? 

For #2, buy the GCM skin above and study by yourself & create your own. I think this would be better solution since it's not recommended to tweak the core code.

Did I tell you I am not VB coder? lol  I myself hit a limitation of DNN system so I am writing my first module too. 

Good luck!