Would anyone happen to know where I can get a DVI wall plate or euro modular insert in a matt black finish?

Any suggestions are most welcome!

Have a look at the module
http://www.aldoussystems.co.uk/acatalog/Online_Catalogue_DVI_Coupler_F_F_2095.html

This will snap into a faceplate such as this
http://www.aldoussystems.co.uk/acatalog/Faceplates___Modules.html

You can buy this these items from
http://www.bitzshop.co.uk/acatalog/outlet_plates.html#aAS304256

Hope that helps