Simplistic CNC Software.

I'm in the process of gathering CNC components to retrofit my
Sherline mill. I have a FROG single axis controller on my Sherline
lathe that I use for threading and as a controllable power feed. I
can maually move the cutting tool to the beginning of the cut, press
two buttons to set as zero, punch in a minus distance to set a pause
point away from the work, punch in a feed rate and a cut distance. I
then press the cut button and it will advance to the end of the cut.
A press of the go button will move it to the pause point where I can
move the cutter in for the next cut or stop the spindle to measure
the work.

I will be making a lot of one off parts and my question is do any of
the software packages support this sort of semi-manual operations? I
want to eliminate a lot of cranking with out necessarily designing
the part from the ground up in a CAD program.

Thanks,

Bruce Buchner