| When i fitted my SWI-X i took off the steering wheel shroud top and rev counter (4 screw in all) and connected into the white/red w/yellow dots wire just below the wheel. If you follow the instruction to the letter the SWI-X can be programmed, though you have to be precise and sometimes act quickly. You can even program a control for the centre left button that doesn't actually do anything with the standard controls.
jlm, it sounds to me that the nodule could be faulty. From above you wiil see i have no experience of tapping into the wire nearer the headunit, but it seems Davbret has got it to work with a connection there.
Its just a thought but is the type of IR controller with your headunit compatible with the SWI-X? Some aren't, there is a list on the PAC web site, i'm assuming you would already have checked this before trying to fit the SWI-X. | 
