Digital BW, The Print

Hi everybody.

I use a EPSON R220 with Epson inks, and I'd like you to give me some 
advices about how can I manage to print a photograph in which B&W and 
color are mixed up. It's a portrait of a girl where I've desaturated 
everything except the lips. I'd like the face in black and white and 
the lips with a vivid red.

I've tried different configurations but the only I've achieved is a 
greenish color instead of the grays. Even more, the print has got 
horizontal strips all along. I've never had these strips in any of my 
other prints.

Do you think tritones or quadtones might be of use in this case? I've 
heard about it but never used.

Thanks,

Rafa