Small correction - You do not need to be acting as pilot in command; you only need to be able to log the time as PIC and xc.
For private pilots building cross-country time for the instrument rating that translates to
- sole manipulator of the controls of an aircraft you are rated for
- performing both the takeoff and the landing on a qualifying xc flight.
Cronnnie, on the splitting, that's fine depending on what you mean by splitting. The rules require that the pilot who logs the time as a xc do the flying including the takeoff and landing. So no mid-route change of the controls. And, safety pilots can't log xc, even on flights where they can log PIC. Flight where you fly somewhere and your buddy flies back are fine. So are flights where you do all the flying and split the costs with a friend because you both want to go to the destination for some fun (which can really make those trips a blast!).
Sorry, for you to bring back to the "I have different pilots and aviation professionals telling me different things," I'm out of town and don't have the references, other than handy. 61.51(e) for logging PIC time and 61.1 for logging xc time. But if you go to the FAA's Chief Counsel interpretation site and put cross country in the search box, you'll easily find the formal interpretations issues in the past couple of years on the logging of xc time by only the person flying the airplane.