I am going to give you a very watered down rundown of what it takes to change over because the details are fairly wordy.
1. Run the head wash function in service mode which empties the machine of ink, cleans it out with cleaning solution, and then empties the solution out.
2. Reconfigure the ink lines behind the ink cartridges to the 4 color configuration. Requires some ink line, o-rings, and brass nuts.
3. Change the ink type parameters to tell the machine it is 4 color now.
4. Turn the machine on and let it run it's fill up sequence.
5. Re-install the machine in Rasterlink as a 4 color machine and download the 4 color profiles.
It takes a fair amount of time to do this so you want to do it while you are not busy. You also run the risk of the head not coming back 100%. You can lower that risk by starting the 4 color fill up with brand new dampers. Overall it's not a huge risk but it does happen once in a while. Mostly with people switching from white to color.