Digital BW, The Print

Clayton mentions in one of the articles on his site that if you're 
using the R220 for BO printing that it doesn't matter what cartridges 
are left in the color slots.  Does that mean that for BO printing I 
can purchase only the Eboni cartridge from MIS (or whatever other 
inkset) and then use the rest of the color cartridges that come with 
the printer?  Will the printer operate in BO mode without any of the 
other cartridges installed?

Thanks!!

Brian