We present a new calibration method that has enabled the production of a 1.4 GHz radio continuum survey from existing HI Parkes All Sky Survey (HIPASS) data. The method will allow accurate flux densities and spectral indices to be extracted from the raw HIPASS data set. Since existing Parkes Radio Telescope band-pass removal software produced flux density and spectral index maps which were not suitable for our catalogue, we develop a new mathematical description for the relationship of the spectral response between the processing software and the band-pass gain. Together with observations of a well-known calibration source, we determine the baseline coefficients for each beam and polarization in the Parkes Multibeam system and produce accurate flux density and spectral index maps. Initial results of this method indicate that the flux density of a source is accurate to ±30 mJy and the spectral index of a source, with S ≥ 1 Jy is accurate to ±0.2, a significant reduction in these errors over the standard HIPASS calibration pipeline. The mathematical description of the relationship of the spectral response between the processing software and the band-pass gain from the Multibeam receiver should be applicable to other single dish telescopes using a Multibeam system, such as ALFA at Arecibo.