I'm not sure what you are asking with "what is the syntax for inserting the CR-LF?".
The LO (Label Origin) command sets the initial cursor position, and also sets the Carriage Return point.
The Carriage Return point is the X-coordinate position to which subsequent CarriageReturn control codes (amongst others) within subsequent LB command(s), will move the cursor to.
The LB (Label) command (which does not itself reset the Carriage Return point) can include various control characters, such as:
CarriageReturn: the character with code decimal 13, hexadecimal 0d.
LineFeed: the character with code decimal 10, hexadecimal 0a.
The DT (Define Label Terminator) command defines the label terminator character, and whether it (if set as a printable character) should be printed or not; default terminator is the ETX control code (decimal code 3, hexadecimal 03).