equipment recommendation - What do I need to photograph paintings with accurate color?

I need to photograph paintings, and also small details of paintings. Color accuracy is extremely important.

Previous experience (not recent, however) with digital photography showed color divergences between the original artwork and the photographed artwork that I found utterly stunning.

The images are going to be displayed in a format not less than 3 feet high, possibly more.

I'll be shooting in a museum setting.

Sigma's option seems to have drastic limitations (proprietary lenses and post-processing software, as well as the lack of live view), although I love the idea of a Foveon-sensor camera for this. I'm not sure whether a Bayer sensor does the trick or not.

What type of gear is essential to photograph paintings with accurate color?

EDIT: The camera/sensor aspect of the question is not satisfactorily answered by the previous thread referenced here.