Okay, I figured it out. You have to make the dxNothing window. Then stack it on top of the client you want it to mimic. Leave the always on top option for this window region to off, because at some point you will need to access something behind the video feeds. When that happens, it's much easier to swap to the mimic'd client from the dxNothing window than it is to alter or move the feeds themselves. From there, you do a 1:1 feed of teh whole client to the dxNothing window. Basically just match the resolution your playing at and set the top & left numerical fields to 0,0 respectively & you have your "Transparent" dxNothing window. Only, it's not transparent, it's just displaying the client over the black backround. Then after that, you have to add each other feed you want to have within your client's screen real estate. Stay away from the synch button tho & be sure to use a program like paint.net to get your feed sizes correct using the "maintain aspect ratio" selections. This will let you make it all nice and pretty. I can explain some of the more granular aspects of this process if needed, though it is frustrating to no end. But, once you get it figured out, you'll smack yourself and never forget how to do it.
Here's my config for those that are curious.. It's for EVE onlineand here's the screenshot of the finished product...This all took me 3 days to learn and configure. I have the 2 screens with a separate swap group per screen. The regions on the left screen have swapping disabled, and the swap group on the right uses an Action Target group to target between the 3 Machariels on hot key press. This is all without interfering with the clients / regions on the left screen. I setup 2 separate hot keys to enable repeater. One combo enables repeater between just the characters on the right screen, using the ATG as the target, and the other toggles repeater between all clients / windows for entering passwords / character login, etc.
Just getting the key maps sorted out with the proper settings to work between the Machariel accounts using the ATG was a task in itself, so if you guys need any further info on this I'll gladly help out with what I have learned in the last 72 hrs....
~DarkMoJo