you need the ej gene in at least one of the rabbits. So you'll tricolour, magpie or harlequin. If you breed two rabbits together that do not have that gene you simply won't get it. Sometimes you can breed an ej rabbit to an non-ej rabbit and not get any kits expressing the gene. Then you take the best of that litter and breed it back to whichever rabbit has the ej gene and voila.. you'll get harlequins, magpies and hopefully tricolours.
In my experience, the quickest way to get tricolours is to breed a charlie to a harlequin.
If you just want harlequin... breed a harlequin or tricolour to a solid rabbit and follow the above. Harlequin is just a solid coloured tricolour.