There is a way to stick multiple resolutions in one .ico file.  For example, I've got one that has 7 images in it:
256x256x32, 48x48x32, 32x32x32, 16x16x32, 48x48x8, 32x32x8, 16x16x8

I'm not sure if there is software out there that builds multiple images for a .ico file on the fly given one image, but it would be handy in this case.  I've been making individual icons and slapping them together after the fact.

If you use one of those icon files for your build, it should bring over all of them.  If you look at VLC, for example, there are a number of icons within it, one of them being 256x256x32.  Keep in mind that if you do a multi-resolution icon file, the first icon in the file is the one that the preview pane will lock onto.