There is a very simple mod that you can do to bypass the RF modulator and use the same connector for a composite output.
It takes a few minutes to do this and works really well.
First job, remove the lid on the RF modulator.
There is a resistor connected to the centre pin of the RF output socket, remove this and bend it up out of the way.
On the outside of the RF module there are 2 wires leading from the modulator to the PCB. These are the VIDEO IN on the left and +5v on the right.
Remove both of these from the PCB.
There is a second insulated hole in the the side of the modulator unit that is unused. Get some wire and strip enough insulation off the end so you can feed it through and then solder it onto the centre pin that the resistor was originally connected to.
As im never going to be using the RF again I went ahead and totally removed the old VIDEO IN and +5v wires. I also removed the old resistor. This step isnt necessary but if you leave them in make sure they are insulated so they can short against anything.
Fire it up and check out the Spectrumy goodness.