Though I wouldn't suggest transporting anything across federal lines (even state lines can become a bitch if you get caught), I figured I'd toss a little tip out there for anyone whose main concern is the drug dogs.
Most people will go with something like coffee ground, because it absorbs some odor and has a relatively strong odor in itself to help mask. At least...it does to us, but dogs can smell roughly 1000 times better than humans (
http://www.aces.edu/pubs/docs/U/UNP-0066/UNP-0066.pdf). They can tell the difference between drugs, explosives, money, and probably almost anything else you can think of...so a simple masking and absorption of odor really isn't enough to keep a well trained dog from finding a stash.
A friend of mine trains "rescue dogs" that find lost people and bodies and I can tell you from watching the training exercises that they can find corpse tissue over 10 feet below the ground, locked in lunchboxes and wrapped in saran wrap.
However...before you get too worried about these amazing finders of stuff that some people might not want found...remember that I am talking about trying to "hide" something from the dog, or hoping it can't tell the difference between scents, etc. Let's talk about another idea...
Since the key to a dog's ability to find things is in the sensitivity of its olfactory senses we can play off that as a weakness.
Mustard Powder...if you want, mix it with some strong powdered Cayenne pepper just for shits and giggles. These powders not only have a strong smell...but are strongly irritating as well. When dogs inhale this, especially when "sniffing" (which is not part of normal breathing for a dog), they end up with huge amounts of irritant inflaming their mucus membranes and effectively shutting down their ability to smell for a while. (Depending on what all you throw into the mix you can actually cripple a dog's olfactory senses for life).
While this might not make sense to everyone...look at it this way...go stare at your 1000W HPS for a few minutes then try to find your way through a dark room you've never been in. It is almost exactly the same concept (as we rely mostly on our sight), except it tend to last quite a bit longer for the dogs and their smell, than humans and eyesight.
(You could get the same effect from using pepper spray/tear gas on them...but I have a feeling their handlers would get suspicious then.)
Anyway....just my two cents on the subject. I still don't suggest border crossing with drugs unless you have some reason that is truly worth the risk.