The LT cable has two spade connectors on one end and a DC connector on the other. The DC connector plugs directly into a port on the back of the control panel. The spade connectors fit right onto the terminals on the transformer.
Want to try to run power without an LT Cable? Okay, but don't say we didn't warn you.
Start with a (22 gauge) two conductor wire. Connect the Panel's positive +9VDC to the positive on the transformer, and the negative from the Panel's GND terminal to the transformer's negative. Achieving this will require stripping the wire insulation and creating a solid connection between the screw terminal and the wire.