I can only speak for my own car ('01 TJ) but somewhat contrary to what others are saying there is an unused line in the steering wheel clockspring which I believe can be used for steering wheel controls.
There is a 3-pin connector going to the cruise control arm, but if you look closely, only 2 pins are used! This is further evidenced by the fact that only three of four pins are used in the harness/loom under the steering column where lines emerge. In total there are 6 lines, by this stage the 2 airbag lines are on their own connector, and there is another 4-pin connector - of which 1 is for horn, 1 is ground, 1 is cruise control signal. I may be wrong but I believe all that is required for _resistive_ steering wheel controls is a ground and signal line so in theory this would work. (Yes you have to re-wire the lines in the steering wheel to utilise the 3rd pin of the cruise control plug, as I have done successfully.)
My problem is that I have found the steering wheel controls (at the wrecker) but I don't think they're resistive. They appear to have a ground, a 12v input line and a signal line. So the control unit is powered, and sends out a signal of it's own, rather than simply controlling resistance to an incoming signal voltage. Has anyone else dealt with this? Do I need to buy a converter - I see they exist on eBay, can anyone recommend one that works please?

Any advice appreciated, thanks.

The cruise control spare pin is of no consequence. You need the extra plug for the remote in the clock spring. You need to get one from a Verada XI. You will also need to make sure it is a KH or later one, so your cruise stalk plug is correct as earlier ones are different.

Then you may luck out having the plug for the back of the clock spring extra plug in your wiring harness, however I doubt it. Yes I can confirm the remote sends its own signals from a 12v source with the remote earthed through the wheel like the cruise stalk and horn.

Mike