OK, here's what I suggest.
Cut the two tracks between PA51 and R507 and R508, at the points marked with the red Xes. A good way to do this is using a pair of sharp side cutters, held vertically, with one point anchored to the board in the area indicated by the "A" and the arrow. You can drill a hole part way into the board in that area to serve as the anchor point for the side cutters. Then, while pushing the side cutters into the anchor hole, bring the other point down onto the tracks and gently open and close the side cutters to cut the tracks. As you cut through the track by opening and closing the side cutters, move the cutting point down until the track is cut all the way through.
Alternatively, get a sharp scalpel from a modelling supply store, and cut the tracks carefully, holding the scalpel just behind the blade and resting your fingers on the board to get fine control. Imagine that you're cutting into a tree with an axe, and the track is the bark of the tree. You need to make two cuts at sharp angles to each other, to make a V-shaped channel cutting through the track and slightly into the PCB material, crosswise to the track. For each cut, press the scalpel firmly into the board and slice across the track. Since you're only making a shallow cut, this will not be hard. When the two cuts meet, the piece of track will just fall out.
Then connect your five wires to the points marked with blue dots. Three of them (the two switched contacts, and the common) can be soldered to the pads where the pins of the radio receiver IC (PA51) come through the board. You may want to remove the old solder first, and make a quick clean joint covering the pad, the PA51 pin, and the wire. (Twist and tin the wire first.) The other two wires can be soldered directly onto the ends of the SMT resistors R507 and R508.
You can use two stereo screened cables, or ideally, a single screened cable with four conductors inside it. The screen(s) connect to the common. If you use two cables, connect both screens to common at the PCB, but only connect one screen at the socket end.
When you strip the wire, unweave the screen (if it's woven) and twist it tightly into a wire. At the PCB end, keep this wire short (less than 1/4") so it anchors the cable to the PCB, and have some slack in the four conductor wires, so if the cable gets pulled, it won't break the thin wires or pull the SMT resistors off the board.
I think I recommended using a socket with a metal collar going through the panel, for rigidity. But if the panel is metal, it's probably better to use the cheaper type of socket with a plastic collar, so the socket is isolated from the metalwork. Otherwise there are two parallel connections between the socket's common (the "sleeve" of the plug) and the circuit's common rail, assuming that the panel is metal and is already connected to circuitry common.