I wrote a daemon to allow on the fly remapping. It works by using uinput subsystem to create a virtual keyboard, listening to the real keyboard /dev/input/event1, and sending the mapped keys to the virutal keyboard whenever a key is pressed.
In order to use it, you need to edit the file /system/usr/keylayout/sec_key.kl, removing (or commenting out with #) the first two lines, and reboot. After this step, the volume buttons are ignored. Now run the daemon (as root). The default configuration is to send SPACE/SHIFT+SPACE for VOL-/+ to firefox and the default browser, down/up arrow to tapatalk, and VOL-/+ to everything else.
The daemon opens a named pipe on /app-cache/.uinput-virtual-keyboard-fifo and can be configured using this pipe.
For example, the command
echo profile com.sec.android.app.ve 231 44
Will map the keys in the video editor to CALL (open phone) and Z.
The daemon is at http://my.svgalib.org/android/pgdn
Source at http://my.svgalib.org/android/pgdn.c
Comments are welcome.