Factory controls in the steering wheel tend to be very specific to the original vehicle's chassis wiring and electronic options that were/are offered within a few model years typically. Another aspect is how do those controls work in the electrical sense? As an example Ford's cruise control or Vehicle Speed Control (VSC) steering wheel switches operate over just three wires which to the casual observer is illogical. In reality those switches are contact points that engage different resistance values that are read by the microprocessor inside the VSC device. All this has a point---trust me.
In order to re-purpose those switches will require EVTM's both from the van and the F-Series to know how they effect their changes. From there you'll have to fabricate a circuit that can "read" the signals they produce but have them act in a different way than originally intended. So then................
If you're up for some serious electrical re-engineering I'd love to follow your progress in all this. I do know from personal trial and error adapting an F-Series instrument cluster into an E-Series has serious challenges very similar to doing the same thing with steering wheel controls.
Best of luck--------keep us updated please.