Automated "Manual CNC"

What I am envisioning is a system consisting of linear scales for
feedback and what amounts to power feed motors (non-servo, cheap). I
want the feedrates to be _extremely_ slow. I would like it if there
weren't any control boards, just a simple interface with a PC through
parallel ports.

The PC would start with a CAD drawing and (knowing what size endmill,
drill, etc.) calculate the XYZ coordinates in .001" steps the
workpiece would have to move to achieve the final part. The PC would
then look at the location of the workpiece and _slowly_ move it to
the next XYZ coordinate position until the part was completed.

This would be _very_ slow, but would be extremely cheap to put in
action with non-servo motors and plain leadscrews and not very
complicated with no calculations of accelerations, feedrates, etc.

This would be automation of the "manual CNC" that you read about for
producing balls and curves on a lathe or mill. You could do the same
thing yourself, but the computer eases the burden of it.

Any thoughts or suggestions on how to go about it with the proper
software? I can handle the interfaces and mechanics of it, but I am
not sure about the software side of it. Is there software that can
calculate the required XYZ coordinates and output them to a text file?