When dying anything, make sure you follow the package directions carefully and test a small piece of the fabric beforehand. Denim should dye easily due to the cotton content, just be sure to wash them separately or dry clean them after wearing.
If you want a new version of this brightening fashion trend, check out Alloy, they have several colors of neon skinny jeans and inseams up to 37 inches for the tall chicks. The pics below are from the company's website and can help give you inspiration to up cycle your predictable faded blue denim into something fabulous. Another tip: If you have white jeans that are stained or yellowing, adding a pop of color can give them a whole new life!