If you mean, change the few colored objects in the layout to black, then it is impossible without changing their color. The few objects that are in color are set to a true-color, which isn't supported in CTB plotting. There are also many objects and nested objects set to a color other than bylayer. So viewport overrides won't work.
If you create a layer for each truecolored object and set those layers' colors to the same truecolor used for those objects, then you could set a viewport color override. This would be the easiest approach while keeping the model space appearance the same.
Another very complicated approach would be to change the drawing to a style based plotting system. This is impossible to accomplish however without custom programming, since it would involve changing the plotstylenames of many nested objects and attribute references.
Architect, Registered NC, VA, SC, & GA.