You can call ME directly (I've done it that way) or there's an online form you can submit to ME (I've also done it this way). I'd have to search for the link -- it has been posted in various threads several times, but I never save it and I should!
As a side note, if you have kids, you know that Orbitz charges extra if you book the kids online, right? You'd have to book just the adults and then call Orbitz to add the kids at no charge. Sorry if you already knew this!