1. Create animation in Blender
2. Move different parts of the character to different layers and render them separately
3. Import all the parts of character to Aseprite and outline every animation layer
It was a pain in the ass to import all the layers by hand so I wrote macros for handle that. But it still makes mistakes sometimes, so hope to see built-in macros redactor in Aseprite some day.
4. Improve the animation by drawing by hand :)