It's an odd aspect ratio (2:1). I assume you hold the phone horizontally? If so, you could use the normal VGA skin, and tell it to scale the height to 66% (we just add that as a new size). The buttons will be a bit short, however the VGA skin has typically generously high buttons anyway. At least that way there's no need to create new graphics or a new skin.
The issue is compiling the Symbian C++ app for series 70. Our mobile phone orbiter guy (Chris) is working on a port for MS Smartphones, so he probably won't be able to get to it for a few weeks. But, if you know programming, you might want to try downloading the Symbian series 70 compiler, checking out the code from SVN, and seeing if it compiles. It may only take a couple hours to get it going. Otherwise, Chris can try it when he's done.