Well, the problem is that the in-dash light switch doesn't turn the lights
on and off anymore.  Rather, it simply allows a signal to pass to the Front
Control Module, asking it to pretty-please-with-sugar-on-top turn on the
lights.

If your truck didn't come with fog lights, the EBay seller is probably
talking about wiring these driving lights up to work off the fog light
setting of the OEM switch, which right now your Front Control Module will
ignore.

Now, that doesn't mean you can't wire them yourself with a separate switch -
one that taps power from the existing headlamp circuit, and uses that to
energize a relay, which then sends battery voltage to the auxilliary lights.

But, if you want it all fancy and stock-like, then yes, the dealership needs
to program that function into the computer for you.

The factory does not supply additional driving lights
to any of their vehicles that I know of.  Fog lights
are almost standard equipment, though.  Hardly see any
vehicles on the dealer lots without them.

There's a big differance between driving and fog.  They
look similar, but function very differantly.  Also, if
you put driving lights into the fog circuit, they will
only come on with the low beams.

The factory does not supply additional driving lights
to any of their vehicles that I know of.  Fog lights
are almost standard equipment, though.  Hardly see any
vehicles on the dealer lots without them.

There's a big differance between driving and fog.  They
look similar, but function very differantly.  Also, if
you put driving lights into the fog circuit, they will
only come on with the low beams.