No, only the buttons that appear in
Customize Toolbar can be added. It is possible, however, to add an
"accelerator" (aka "keyboard shortcut" and "hotkey") to do so. Following is my
...\Media Center 15\Data\Custom Resources\Resource.xml...
<!--
Media Center Resource XML (Default / English)
-->
<MJRS version="1.0">
<!--
ACCELERATORS:
Key: semi-colon delimited list of key strokes to be pressed (see list below for special keys)
note that the only valid combinations are: [Key], [Key];Ctrl, [Key];Ctrl;Shift, [Key];Alt
Type: the type of command (defaults to MCC)
MCC: the command is an MC command
Program: the command is a program to run
Command: the MCC command index / name of program
Param: the parameter for the MCC command / program arguments
TranslateFlags: flags that determine when and how an accelerator is translated (binary or'd together)
1: don't translate in edits, comboboxes, and other data entry controls
2: don't translate in fullscreen mode or theater view
4: don't translate in any type of popup window
8: only translate in fullscreen
16: don't translate in IE, VB controls, or other unknown rich controls
32: targets playback engine / display (DVD, image playback, etc.)
64: only translate when Action Window is focused
NoShowAsShortcut: 1 if you don't want MC to show this shortcut in menus, tooltips, etc.
Global: 1 if you want the accelerator to be translated even when MC doesn't have the focus
Special key list: Insert, Delete, -, +, Right, Left, Up, Down,
NumPad0, NumPad1, NumPad2 (etc.), F1, F2, F3 (etc.), Backspace, Enter, Escape,
Apps, Page Up, Page Down, Home, End, Space, Print Screen, Tab
Remember that order is relevant when the same shortcut appears multiple times.
-->
<ACCELERATORS>
<!-- Rate current song -->
<Entry Key="Ctrl;Shift;0" Command="10023" Param="0" Global="1"/>
<Entry Key="Ctrl;Shift;1" Command="10023" Param="1" Global="1"/>
<Entry Key="Ctrl;Shift;2" Command="10023" Param="2" Global="1"/>
<Entry Key="Ctrl;Shift;3" Command="10023" Param="3" Global="1"/>
<Entry Key="Ctrl;Shift;4" Command="10023" Param="4" Global="1"/>
<Entry Key="Ctrl;Shift;5" Command="10023" Param="5" Global="1"/>
<Entry Key="Ctrl;Shift;NumPad0" Command="10023" Param="0" Global="1"/>
<Entry Key="Ctrl;Shift;NumPad1" Command="10023" Param="1" Global="1"/>
<Entry Key="Ctrl;Shift;NumPad2" Command="10023" Param="2" Global="1"/>
<Entry Key="Ctrl;Shift;NumPad3" Command="10023" Param="3" Global="1"/>
<Entry Key="Ctrl;Shift;NumPad4" Command="10023" Param="4" Global="1"/>
<Entry Key="Ctrl;Shift;NumPad5" Command="10023" Param="5" Global="1"/>
<!-- Play playlists -->
<Entry Key="Ctrl;Alt;1" Command="30007" Param="Keyboard\Albums" Global="1" />
<Entry Key="Ctrl;Alt;NumPad1" Command="30007" Param="Keyboard\Albums" Global="1" />
<Entry Key="Ctrl;Alt;2" Command="30007" Param="Keyboard\Highly rated" Global="1" />
<Entry Key="Ctrl;Alt;NumPad2" Command="30007" Param="Keyboard\Highly rated" Global="1" />
<Entry Key="Ctrl;Alt;3" Command="30007" Param="Keyboard\Not recently played" Global="1" />
<Entry Key="Ctrl;Alt;NumPad3" Command="30007" Param="Keyboard\Not recently played" Global="1" />
<Entry Key="Ctrl;Alt;4" Command="30007" Param="Keyboard\Random" Global="1" />
<Entry Key="Ctrl;Alt;NumPad4" Command="30007" Param="Keyboard\Random" Global="1" />
<!-- Set/reset "Review Mode" (30 seconds from 30 seconds in) -->
<Entry Key="Ctrl;Alt;8" Command="10031" Param="122910" Global="1" />
<Entry Key="Ctrl;Alt;NumPad8" Command="10031" Param="122910" Global="1" />
<Entry Key="Ctrl;Alt;9" Command="10031" Param="0" Global="1" />
<Entry Key="Ctrl;Alt;NumPad9" Command="10031" Param="0" Global="1" />
</ACCELERATORS>
</MJRS>
This illustrates how lists can be assigned to hotkeys using
MCC 30007. My choice was to define global hotkeys for a small set of smartlists maintained in a "Keyboard" playlist group. If I want to make changes, I first consider modifying one or more of the smartlists before changing the accelerators.
It's unfortunate MCC's can't be assigned to toolbar buttons, but hotkeys do have broader application. They can be used globally and assigned to remote buttons.