In this tutorial I'm going to be using Alt gr and the numpad.
;next song <^>!Numpad6::Send {Media_Next} return ;previous song <^>!Numpad4::Send {Media_Prev} return ;play/pause <^>!Numpad5::Send {Media_Play_Pause} return
Let's break it down,
"<^>" is Alt gr.
The exclamation mark tells the compiler that the previous key (In this case, Alt gr) must be held down in order for the following button (Numpad x) to execute the command.
The semi-colons will comment out the rest of the line.
The two colons after the hotkeys tell the compiler that we're about to write whatever we want executed.
"Send" is a method we use to send a message to whatever global variable the current music state is. Followed by the requested argument.