Unfortunately that's just not true. If you jack on the sill joint, you'll likely cause some distortion of the sill.
See the picture in this post.
I once refused to take delivery of a new Panda with sill damage caused by a franchised dealer during the PDI; fortunately they had another car of identical spec in the compound.
http://www.fiatia.com/fman-681.html
that is for a punto, but it has the same style jack. there are arrows on the sill trims and a cutout on the plastics where the sill joint is to locate the jack.