On Wed, 30 Apr 2008, Kevin Milburn wrote:

I can now use all the extra keys which result in a keycode of less than 
255, which appears to be a limitation within the Xorg evdev driver.

Yes, exactly. See for example 
http://bugs.freedesktop.org/show_bug.cgi?id=11227

Secondly, the primary reason for trying the above was to obtain the 
scancodes 

Just a sidenote -- USB keyboards have concept of "usage codes", rather 
than "scancodes".

so I could alter the keycodes to work with X.  Trying to alter one of 
the working scancodes (e071) to a new keycode using the setkeycodes 
command failed with an 'Invalid Argument'.

Newer kernels have hidinput_setkeycode() callback, which should allow 
setting the usage code <-> keycode association using 'setkeycodes'. Could 
you please post hid debugging output?

-EINVAL should be returned only in the following cases:

	- (keycode < 0 || keycode > KEY_MAX).
	- the usage code you have specified is not supported by the 
          keyboard, according to its report descriptor

(see hidinput_setkeycode() code).

Further research lead me to a comment indicating that setkeycodes does 
not work on USB keyboards.  If this is correct (which it seems to be), 
is there any other way of altering the keycodes generated by the kernel?

The support for setkeycodes working with USB keyboards has been added in 
commit fe7ba31fead.

-- 
Jiri Kosina
SUSE Labs