This is most definitely possible... Though was extremely difficult to figure out.
See here:
https://github.com/bradgearon/eso-stuff
From line 121-122 I in my mod I call this (a method that does just that but is intended to consolidate and move things from your inventory to your bank).
Code:
-- consolidate source
moveItems(bags, BAG_BACKPACK, BAG_BACKPACK)