how to I create a new supported keyboard in gnome

[teaker1s]

basically I can get a script running which will allow me to have custom keyboard as system-preferences-keyboard doesn't have a suitable model.
what I would like to do is create a new entry in 'system-preferences-keyboard'
with the keyboard and its custom media buttons.
so far I can get the keyboard to appear as an option but I'm not sure where to edit the keyboard so it use in 105 layout then a set of custom keys for other things

thanks

[teaker1s]

okay guys I can see have got to the stage where I by on 'system-preferences-keyboard' I have defined a new keyboard-now If anyone knows I'd like help on how xorg defines each model.
once I know the location that say a microsoft keyboard goes for it's configuration I can copy and modify the files to suit.
I have looked at keys and symbols but I believe there are specific model settings I have yet to find