Hi, Boxer. Welcome aboard! You could mix a fine paste of mortar and color it to match, but that might be an impossible task. It could make the brick look like it's got the measles! There is another option, however, and may give you some other opportunities. A product called 'Brickit'. It's easily applied, realtively cheap, and comes in various colors, besides.
http://www.brickit.com/
Our project is to recover a portion of the house exterior, and have found these people to be very courteous and helpful.