migrate SQL Server geography data to PostGIS geometry data
I figured it out.  I used a query for the SQL Server source that converts to POINT text using: 


  geometry::STGeomFromWKB(myPointColumn.STAsBinary(), myPointColumn.STSrid).STAsText()


That was all it took.  Now whether the point will be represented in PostGIS the way I intend it to I can't say at this point, but I'm hoping so.