I was hoping this was included too. I found this in a spotify thread
add the following the toastify.xml file located in the toastify folder.The folder is %localappdata%\Roaming\Toastify
<Hotkey><Ctrl>false</Ctrl><Alt>false</Alt><Shift>false</Shift><Key>MediaPlayPause</Key><Action>PlayPause</Action></Hotkey><Hotkey><Ctrl>false</Ctrl><Alt>false</Alt><Shift>false</Shift><Key>MediaStop</Key><Action>Stop</Action></Hotkey><Hotkey><Ctrl>false</Ctrl><Alt>false</Alt><Shift>false</Shift><Key>MediaPreviousTrack</Key><Action>PreviousTrack</Action></Hotkey><Hotkey><Ctrl>false</Ctrl><Alt>false</Alt><Shift>false</Shift><Key>MediaNextTrack</Key><Action>NextTrack</Action></Hotkey>