Need Help! Converting stepper to servo

hi friends,
i have received my sieg sx3 10 days ago, i am very happy with the result that i got from the machine.
and like everyone else i want to convert it to cnc. i have made a cnc router in past with stepper motors. and thats why i want to go with the servos for the sx3.
i have found a wonderfull link about "Digital Calliper". here it is=
Voltages: Logic and Power

but using a digital calliper and a arduino we can read the position of the calliper on a computer. SO MY IDEA IS to us 3 calliper and connect it with PC and make a software (VB6) which will read the value from calliper and then gives step dir commands to the stepper driver. it works the same way like if we hocked up a encoder at back of an servo motor.
so as far as i think, by using calliper as DRO and with the help of an self made software i can use any stepper as servo.

so guyz, what do you think? am i missing something? will this concept work or not? and is there anyone on cnczone who have tried anything like this?

i am waiting for your suggestions guyz.