I have Logitech S510 multimedia keyboard. It is wireless and is connected via USB.
So some keys (like "Stop", "Play", "Volume Up"...) are working "out of the box", after making ~/.Xmodmap file...
But some keys are not even seen in xev program. As I understand that "happens" because its keycodes are >255.

So with command showkey -k I've got these keycodes for the keys:
Key Keycode
====== =======
Mode-F2 421
Mode-F3 423
Mode-F4 425
Rotate 371
ZoomIn 419
ZoomOut 418
Zoom100% 420
Shuffle 410

But as you can understand making line in ~/.Xmodmap like "keycode 421 = XFWord" don't do anything!
Using this manual I can get scancodes too (and I've got them).

So I know how to get keycodes and scancodes, I know how to use ~/.Xmodmap, but I don't know how to make them work together!
Question is: Does anyone know how to access all the additional keys on the Logitech S510 keyboard?

I'have found some manuals exactly for my keyboard, but they are for other distros, and don't work for openSUSE - I get errors on setkeycodes xxx yyy...
Looks like on Gentoo there is different "codes".