Defining my own xkb model map

[Cameron Hutchison]

How do I define my own xkb model map, preferably with as little change
to the existing conffiles such as just adding new files?

I want to define my own model because the logiinkse one that I'm using
now has multiple definitions for the XF86AudioMedia and
XFAudioRaiseVolume keysyms. Due to the way that gnome-settings-daemon
handles these keys, it fails to recognise them when duplicates are
present if the incorrect duplicates have a lower keycode than the
correct ones (as is my case).

Having defined a new xkb model, I'd like to be able to select it from
the System->Preferences->Keyboard Layouts tab, and not have to resort to
a login script to set it up.

Thanks