Yes, you can see if Eutronix or Rob can get you the proper extension cable that includes the correct wire.

You could also just do it yourself: add the necessary pin to the connector that plugs into the tuner module and make your own blue antenna remote wire coming off of that pin.

I think (not certain, someone needs to back me up here), that there are eight pins on the tuner connector, and seven of them are used on the sled-to-tuner plug. The one remaining pin that is currently unusued on the connector is the one that you want to be the antenna remote wire.

If you decide to go the D-I-Y route, don't just hook it up and hope it works. Check the voltage on that pin with a voltmeter as you turn the tuner on and off from the player's front panel. If it behaves accordingly, then you've got the right pin.