Coach Kevin Smith is the Running Backs Coach at Ole Miss. In the video presentation below, he describes some inside run footwork fundamentals that he teaches to the backs he coaches.
You can view Coach Smith's entire video on Inside Run Drill Tape for RBs on Glazier Dive.
Some of the Key Coaching Points
Good eyes and good feet are as important as speed for a running back.
Speed kills, but skills pay the bills. A back who isn't as quick can still gain positive yards with exceptional footwork.
A running back will see a different first and a different second level picture for every snap during a game. That is unique to running backs, so Coach Smith focuses on working on those pictures every day.
You have to implement your alignment details, landmarks, and aiming points into all of your running back footwork drills.
For inside zone, Ole Miss' details are:
1) Press the Crack of the Center
2) Run with tempo (not full speed)
3) Square shoulders
4) Press the line of scrimmage
If any of these details are off, the running back will see a different picture. Details change pictures, so you have to be detailed in everything you do.
Tie your technical details into your schemes and work on movement that the backs will see in a game.