I got this a few years ago from a guy that was with the team that kept the NCAA game going. It appears to be pretty similar to Kiffin's.
He told me they developed it through countless hours of testing and it was accurate to the EA speed ratings or something like that. I can't remember exactly but I've used it ever since.
4.26 : 99
4.27-4.28 : 98
4.29-4.31 : 97
4.32-4.33 : 96
4.34-4.36 : 95
4.37-4.38 : 94
4.39-4.41 : 93
4.42-4.43 : 92
4.44-4.46 : 91
4.47-4.48 : 90
4.49-4.51 : 89
4.52-4.53 : 88
4.54-4.56 : 87
4.57-4.58 : 86
4.59-4.60 : 85
4.61-4.62 : 84
4.63-4.64 : 83
4.65-4.66 : 82
4.67-4.70 : 81
4.71-4.74 : 80
4.75-4.77 : 79
4.78-4.80 : 78
4.81-4.83 : 77
4.84-4.87 : 76
4.88-4.90 : 75
4.91-4.93 : 74
4.94-4.97 : 73
You get the picture.
Like I say, looked pretty similar to Kiffin's when I glanced at it.