I currently have a Dish 500 connected to a 508 and 510 Receiver. I would like to upgrade the 510 to the 522 or 721 in order to get two tuners. My problem is I only have one wire feed from the wall to the receiver. I understand you need two wires from the wall in order to take advantage of the two tuner feature of the 522/721. Could someone tell me how and if it is possible to split the wire from the wall to the 522/721?