Where do menu icon files go in phone FS

Hi,
I recently purchased a W715. I have so far unbranded the phone and loaded the latest generic Sony Ericsson firmware. I am also getting into modding the menu file layout using the menu.ml file as I wanted some minor changes. The menu layout for the top row now goes Internet -- Games -- Applications

Removed the PlayNow icon as I don't need it and the Entertainment apps now come under applications. Where I am getting stuck is that I want to change the Games icon. currently the games link is using the PlayNow Icon. I also want to change the Application icons as it is using the Entertainment icon. I am working out how to change the menu.ml file to load other icons, but not having any luck so far.

I am not able to work out where in the file system I can put the icons and then have them called by the menu.ml file.

Can someone please help me. I am using Phone Explorer to browse the phones file system and am able to upload any files needed etc.

Thanks.