absolute to incremental conversion

Hello all, I am doing the DXF to Gcode conversion from my TurboCAD
3D Standard with a MaxNC DOS program. This gives absolute
coordinates. To get incremental coordinates, I import the Notepad
Gcode into Excel and save my recalculated Gcode back into Notepad.
It works fine, but I was wondering if there were other low-cost
methods to convert long strings of coordinate values from absolute
to incremental. Thanks! Charles Hixon