The standard location for your own modmap is ~/.Xmodmap [noobs: "~" is your home directory]. The format of the file is the same as xmodmap -pke gave you in the last section:

keycode (number) = (key name)

You know the number ( the keycode), just the key names are in the dark. One could use "F13", "F14" and so forth for the extra keys, but there are several names which describe the function of your keys perfectly: "XF86AudioMute", "XF86Mail", ... . There is a list of this names in

/usr/share/X11/XKeysymDB

With this knowledge you can create your own modmap. If this is too much work for you, have a look at the "Maps for Keyboards" section with predefined maps for several keyboard types. You can test your own map with

xmodmap $HOME/.Xmodmap