Custom workspace arrangement?

Hi everyone! :-) I have configured eight virtual desktops (or workspaces, or whatever they are called) on my stock up-to-date F16 KDE. They are automatically arranged in 2x4 fashion, two rows with four columns in the pager. I want a 1x8 geometry, so that there is no desktop "above" or "below" the current one. I can configure the pager to display the desktops in this fashion, but the rest of KDE somehow still "knows" that desktop 5 is "below" desktop 1. This is visible when switching desktops via the keyboard, or using some 3D desktop effects, or otherwise. So, how do I configure KDE to arrange my desktops into a 1x8 geometry? The point is that I want to use right/left screen edge to move to the next/previous desktop, but I do *not* want anything to happen when I hit the top/bottom screen edge. However, I cannot configure screen edge action separately for each edge, and OTOH I cannot arrange eight desktops so that there is no desktop above/below the current one. I'd appreciate any pointers on how to disentangle this mess. ;-) Best, :-) Marko