I'm a big anki fan but I don't think it would help much for IM simply because the material to cover is too vast and not really amenable to flashcards. Especially this early in the year, you really need to get practice doing questions because they are deceivingly similar yet dramatically different from step 1. UWorld is the best for IM and people who get through all of their IM questions usually do well on the shelf.
I remember looking at the shared anki decks too but wasn't that impressed.