I try this method, go to Developer Menu --> Component Test --> C_couios --> Keyboard Manager --> Keycodes.
Then press any key You like, then it would occur on the screen :
Sample press key numeric "5"
Keyname : KEY_5
Keycode : 0x35
Resulting, key numeric 5, has name "KEY_5" and key code (in Hexa) 35, converted to decimal then would be 53
By those method, i've found key code for [i]camera[/u] on EL71 was 14 (Hexa) or 20 (Decimal), but still couldn't found any way for mediaplayer and play/stop key.