I have successfully ordered Aztekium seeds from the US on a few occasions. As long as it has nothing to do with lophophora you could probably slip a few packets through customs. Having said that I do not publicly support breaking the law and there is always a risk that your seeds could be confiscated. Also you could receive an official warning not to do it again.It's also important to point out that they can, at their own discretion, enforce some pretty hefty fines for flagrant breaches of the law.
I would strongly recommend a bit of research. I do vaguely, remember reading a thread on the forum about importing. If you can locate it in a search it may answer a lot of questions without the need to endure mind numbing government nonsense. If not try the AQIS or customs website. If you can stomach the endless pages of bureaucratic diarrhea you will probably find all the information you need to make a proper risk assessment.