[code:1]
REM batch file to launch those 3 wow's
REM Upper right
pathofwowdir\maximizer.exe --margin 0,Bottom Margin,0,Right Margin
REM Upper Left
pathofwowdir\maximizer.exe --margin 0,Bottom Margin,Left Margin,0
REM Bottom one
pathofwowdir\maximizer.exe --margin Top Margin,1,0,0[/code:1]

The 0 means that there is no margin needed
The Bottom Margin is where you want the Top windows to end (from top to bottom..probably halfway split on your screen.. so just use your screen's resolution and divide it in half)
The Right, resp. Left, margins is that vertical split in the middle (use your own resolution and divide it in half..)
The 1 I used so that there's 1 pixel left on the bottom of your screen in case you wanted to have your toolbar to pop up (make 0 if this isn't needed)

Unless you want the big one on the bottom not stretched out, I'd suggest just playing around with the margins a bit..

Of course Maximizer does provide a few other options, but this should get you started.