The package is in a chest. the chest is in a 2x3 room. There is a (locked) southfacing door in the southwest corner and a northfacing secret panel in the northeast corner. the middle of the room is filled by an impenetrable magical barrier. The chest is in the northwest corner. I somehow doubt there is another panel in the northwest corner. (but there might be can anyone verify/deny this?)
How I tested this on Avernum 3 v1.0. Talk to Paolo to get the mission to retrieve the herbs. Travel to Delis. Step through the panel on the north sid of the inn. Move first charachter adjacent to chest. Search chest.