Sure can. Basically you join in catergories, ie, figures, unleashed, deluxe, vehicles, etc. When you sign up, just pick the figs and items you want. Anything you don't want, just leave the quantity "0". For example, when I signed up, I had already ordered a case that had Aayla, Barris and bunch of other figures in it. I just didn't add them to my order for kebco. Once your initial order goes through, you don't have to worry about ordering again. Its automatically done for you.
I'm a semi-completist so having one of every figure is not a problem for me. If you, however, don't want one of every figure, then kebco might not be for you. If you order just one of say an unleashed fig, ultra fig, vehicle or speederbike fig, then all of those types of items will be sent to you in the future. I'm sure you can cancel certain items if you want to, but I've never actually had to do it, so I don't know how difficult it would be. If you have any more questions, I'm sure Scott at kebco would be glad to answer them for you.