Stephen,
What if your resolution is not available as a platform? I'm using a Windows laptop with screen resolution 1600x900. This resolution is not one of the supported platforms. I did try adding a section to Screensets.ini named [Win32_1600x900], and placed the Win32_1280x1024 as the first entry in this section. However, after I publish and reset my client to download fresh code it still isn't using my Win32_1280x1024 platform code.
Thanks
Tim