I noticed most of these guys are doing the rattle can bed bed liner. I was wondering how tough it actually is in the bed. I used the hurculiner roll on a couple of times and you couldn't beat it for being tough and anti skid. My only complaint was it faded really bad after a couple of years.
Fishnalaska is right, sand it enough to get the gloss off of it, clean it really well with laquer thinner and go to town with your liner. With the roll on it was easier to keep it off stuff you didn't want black. if you are spraying it make sure you cover everything up that isn't going to be black. Once its on there its not coming off easily.