Hello. You might consider another alternative to the TouchFLO3D or WM6.5 interfaces, SPB Mobile Shell:
http://blogs.zdnet.com/cell-phones/?p=2120 You can watch the YouTube video to see if it is right for you. You seem to be able to flip through emails without opening them. The problem with reassigning buttons is that the function needs an executable or else another button must do the function. There is a program AE Button Plus:
http://ae.inc.ru/aebplus.php However, you have to have a d-pad or some way of scrolling with a button already to map it to the volume controls. Not sure about one-handed operation or if this helps...