No prossible thru one field. Little complicated. In your case, you may have to use 4 checkbox fields (choice1,2,3 in first field, choice4 2nd field, choice5 3rd field, choice6 4th field) one below the other so that the first three can be of one color(default-black), choice 4(Blue), Choice5(default-black) and Choice6(Blue).
If you use a layout region, you should be able to get the text a predictable size so that you can put a background bitmap behind it. You can also use a background bitmap in a table cell, but the user can adjust the font size upward so you can’t tell how many pixels high the letters might be.