You may need to construct planting pockets with some rocks to get things started. Terracing it would help, but would be a larger project. Vinca might work.

Here is a link that might be useful: Dry Shade

i don't know about your zone, but in my area, pachysandra is used everywhere for exactly your description. we're trying the same to hold back erosion on a shady bank in our back yard.

also other shady groundcovers that i just put in (b/c i'm bored with pachysandra) are sweet woodruff (white flowers late spring, very pretty), dead nettle, vinca, and sedum (some varieties grow in anything sun shade rock crevices)..

A gardening book suggested euphorbia sp. robbaie (Robb's spurge), which it describes as "a real thug of a plant," for spaces where nothing else will survive. I bought some for a dark corner--haven't planted it yet, but it's very pretty. You might put some in and see what happens--but if it shows up at your door demanding money, don't blame me!