The only way to really do this, with an existing skin, is VERY complicated! Most of the skins have the icons, labels and such on the images. This would make for a reversed image for ALL of those skins.
For skins that do not have icons, text labels and such on the on/off/down images,(Very few skins) would also be very difficult to do. You would need to flip the BG image first off. Then you would need to change EVERY image and EVERY button coordinate on EVERY skin to show up in the new location.
As for the << > >> (Rewind play and FF buttons, they would now be >> > << if it was flipped...
This doesn't even begin to touch on the top bar in most skins where track time, online indicators and such are located, as they would have to be left alone for the most part.
The bottom line, is plain and simple, there is NO easy way to do this. Just make a skin from scratch, or get a good cardio workout, and reach that extra 5 inches (Sorry, 127mm) across the screen
I personally do not think that the menu's on the left is a left/right hand drive issue, its just the way things are in 90% of the world. Most cultures read from left to right. That's why the Start button is in the bottom left of the screen. Also 99.9% of navigation on a website, the menu is on the left side of the screen. When you are in any type of explorer tree, and open a sub menu, it branches off to the right ect.
All of this (Except for the part of it being hard to do for a skin) is of course just my 2 cents worth, and my opinion.