They were shipped out via convoys (the same convoys used in the slide show presentation taken by aerial satellite photos by then general Colin Powell while trying to make the case of going to war)as well as converted commercial airlines....
Many were in fact constructed as mobile labs and some even had skids built under the labs. My friend has talked about writing a book about his experiences in Iraq. He has utter contempt for the Iraqis who were constantly playing con-games with the entire team of investigators.