I did the OEM Cruise update to an 03 XLS Escape in 2005, with a lot of talking to people on escape-central.
The XLS Escapes tend not to have the wiring from the dash to the Cruise Module (All wires), and from the Engine Harness to the Dash (Speed Sender output from the ECU) in the harness. This means there is a little custom work required (But its worth it). The CLockspring does have the connectors, and they are wired back to the (in your case D/S) kick panel. The plug for the Cruise Defeat Switch (on the brake pedal) should also be there.
To do it right - You need to pick up the Speed output from the ECU in the Engine Wiring Harness under the battery, and deliver it to the Cruise Control Servo. You also need to replicate all of the other wiring for the Cruise Servo - which is available in the connectors at the D/S Kick Panel. I used some trailer wire, ran the new harness under the dash to the (P/S in the US, but our D/S) kick panel, out through the Guard with the indicator wiring, and into the Cruise Servo.
Worked a charm. If you wire it correctly the Dash Light for Cruise also works.
Cheers
Nigel