I set Colemak as the system default layout. Also, I changed the keyboard interface to PS/2. Below is the status.
penguin@theblue:~$ xinput list
⎡ Virtual core pointer                        id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                  id=4    [slave  pointer  (2)]
⎜   ↳ stylus                                      id=6    [slave  pointer  (2)]
⎜   ↳ eraser                                      id=7    [slave  pointer  (2)]
⎜   ↳ cursor                                      id=8    [slave  pointer  (2)]
⎜   ↳ pad                                         id=9    [slave  pointer  (2)]
⎜   ↳ Wacom BambooFun 4x5                         id=12    [slave  pointer  (2)]
⎣ Virtual core keyboard                       id=3    [master keyboard (2)]
    ↳ Virtual core XTEST keyboard                 id=5    [slave  keyboard (3)]
    ↳ Power Button                                id=10    [slave  keyboard (3)]
    ↳ Power Button                                id=11    [slave  keyboard (3)]
    ↳ AT Translated Set 2 keyboard                id=13    [slave  keyboard (3)]
When I log in terminal Scroll_Lock turns on LED light when it's pressed. But, Xorg deactivates it. I ran xev to check it works. It returned 
keycode 78
keysym 0xff14
Name Scroll_Lock
'$ xmodmap -e "add mod3 = Scroll_Lock' or
'$ xmodmap ~/.xmodmaprc'  in gnome-terminal activates it. 
So I assume putting above code in ~/.xinitrc would activate Scroll_Lock. But it fails to do it. I tried three different methods so far without success.
xkb_keymap {
    xkb_keycodes  { include "evdev+aliases(qwerty)"    };
    xkb_types     { include "complete"    };
    xkb_compat    { include "complete"    };
    xkb_symbols   { include "pc+us(colemak)+inet(evdev)+terminate(ctrl_alt_bksp)"    };
    xkb_geometry  { include "pc(pc104)"    };
};
When the system default layout was Qwerty, xmodmap remapped keys during Xorg startup.  Under Colemak, it doesn't.
						
										
							 
						Debian GNU/Linux Jessie NitroType TypeTest