Samsung Galaxy Tab 2.7" home screen wallpaper
If you're just trying to set it for home screen, try either Wallpaper Wizardrii mentioned above or Image 2 Wallpaper (com.shirobakama.wallpaper).

However if you're going for lock screen then IMO you're out of luck, at least on Samsung devices. None of the 2 above apps acknowledge Samsung's separate lock screen wallpaper and thus would not touch it.

If you're so desperate for this feature that you're willing to pay extra effort, flash non-Samsung-based custom ROMs like CyanogenMod - Tab2 has plenty of them.