Probably not until you either get Froyo or root access.
LiveWallpapers.apk and LiveWallpaperPicker.apk need to be pushed to /system/app/. You can use a file manager to see if these two apk's were added. If not, then you're looking at waiting.
I don't have the phone, and haven't been in a Sprint Store since it came out. Try downloading a free one from the market. Then menu/long press-- wallpaper and see if the live wallpaper switcher app is in there. You should get something like this: http://gadgetsdna.com/wp-content/uploads/2010/03/Android-Live-wallpaper.png
If you don't, then live wallpapers aren't on board. Also, you can't sideload these like you can a typical app, it has to be pushed to /system/app, which if you don't have access to via root, then it won't work.