Am I right in assuming you mean something along these lines?
Dust will enter it through any gaps, especially the slider and CD slot but also around the buttons. If you depend on the ones you have for your livelihood and/or the possibility of a couple hundred bucks plus time for repairs after you get back scare you, it's probably best to leave them at home. If you can stand a little risk, there are ways you can minimize how much dust gets in and hope you get lucky:
Have a completely sealed container you can easily put it in when not in use. Be diligent about using the container - if you aren't actively using the CDJ and standing near to it, put it in the box. If it's not in the box, the box itself should be sealed so it doesn't fill with dust.
Perform from a sheltered location - top and 3 sides around you. The back of a box truck is great for this. A carport, yurt, etc would also work. I know of one DJ who built a huge steel and plastic cage to play inside - overkill, but pretty cool.
Have a backup music source you can switch to if the wind picks up or you want to leave your post for a while.
Some sort of shield around the unit would also help.