||The South African 'Lo' systems are south-orientated. That is, the positive axes are south and west, rather than east/north. Several people have told me that you define the coordinate system to match the given parameter values, except for the scale factor. Make it negative and that will allow the 'Lo' data to display properly in ArcMap.
You'll have to figure out which zone to use. EPSG Geodetic Parameter Dataset (http://www.epsg-registry.org) has that information. The data could also be on the Cape or Hartebeesthoek94 geographic coordinate systems (datum). Both of those are supported, so when you define your new projected coordinate system, pick the appropriate GCS to base it on.