You are not understanding what I've said.
As I said, you can 'multi-select' as many single images as you want which will create the animation. Use shift or ctrl key to select a range of individual images. A sprite strip is not necessary.
From the manual:
[quote:3ivqrvqm]Import frames - from files... Opens a dialog to select one or more image files from disk. All the selected image files are added as animation frames.