It is possible to only paint the pink sections of the bike and I would have a professional paint shop do it for best results. After stripping the frame down to nothing, they will scuff the entire surface of the bike to allow the new material to stick and use an Adhesion Promoter like Bullydog to prep the surface. Next step is to tape up the whole bike leaving only the pink area to be exposed so the new color of choice can be applied. After drying, the tape is removed, light scuffing if needed to soften the edges of the new paint, and finally a clear coat finish is applied to the entire bike which can be gloss, satin, or flat depending on your preference. I'd guess it would cost about half the price of a replacement frame unless you're sporting an S-Works frame?