Most good repro cpo's are reverse printed on lexan film. That protects the artwork.
If you get yours printed on vinyl, a laminate overlay is probably a good idea. Also check with the printer and make sure the adhesive is not water soluble (most aren't, but it doesn't hurt to ask). When you go to apply the cpo, you can use a soapy water solution or Windex to spray down the cp before you put the cpo on. That keeps the adhesive from sticking down while you are positioning the overlay. Then use a window squeegee to smooth out any bubbles and pull the water out from under the cpo. Any residual water under the cpo will dry within a short time and not affect the adhesion of the cpo to the control panel.