i used a cone cutter ( a hole saw would do just aswell ) to open the area up to about 1" across which enclosed the original hole and imobilser slot, then fitted a textured grommet like this into the hole, looks almost factory...
these from R do the trick nicey, obviously u would needto measure exactly the correct size..
i have used these to fill old LED holes and imobilser holes etc in the rest of teh dashboard, they fit nicely and are the same colour
http://documents.rs-components.com/i...82088956369113