Yes, resize it to 960*800 and then you can select the whole thing... However, even if you do so, and keep the wallpaper to stay still (I only know launcher pro) it still will not show the whole wall paper as the actual 'viewable piece is still like 480*800...
I really don't like scrolling walpaper myself and have always just edited my backgrounds in photoshop so that the '480*800 piece' that always shows is what I want to show... It can be tedious at first but once you have a template saved you can edit it to any image you wish...
Try this if you wish to just resize on the phone and make things simple:
http://www.appbrain.com/app/reduce-photo-size/com.shoozhoo.imageresizer which I found in this forum
http://forum.androidcentral.com/android-applications/13979-image-photo-resize-app-2.html