Hi Adam,
Sorry, my fault, I did not explain it very well.
If your CAD/CAM software is always going to create arcs using Absolute IJ Mode then mod. the post processor you are using to create the Gcode to include G90.1 at the start of the code (if it uses Incremental then G91.1 at the start of the code). This will save you having to make future changes to the IJ mode manually.
Tweakie.