Do you mean ‘adding latitude/longitude axis variables’? Dimensions and axis variables are different things. You already should have dimensions named ‘latitude’ and ‘longitude’.
Have a look at e.g. Monthly average tropospheric NO2 vertical column for an example on how to derive lat/lon variables and squash them as part of the post-operation (although with recent HARP versions you are better of using the ‘-ar’ option / ‘reduce_operations’ argument).