The way I set it up is slightly different from the way Greg does it but I have tried both ways and there doesnt seem to be any difference so I will tell you the way I do it.
Steps per unit is the amount of pulses per rev, mine have 2000 line encoders so that is 4 x 2000 =8000 pulses per rev which is steps per rev/unit
Velocity is the Max speed that your servo will do.
Accel will all depend on what your hardware can do without faulting or what you are happy with, so best start low, maybe 5 or so and see how things go. If it takes too long to spin up then increase, if it faults then decrease.
Now for one very IMPORTANT thing I have never seen mentioned anywhere is you MUST have the pulley max speed set to whatever your max velocity is (presuming 1:1 setup) and make sure you are in the pulley range you have set up in.
Hood