Sandpaper and a buffing wheel. Use 400 grit, then 800, then 1000 or higher depending on how much shine you want, then use a buffing wheel on either a bench or die grinder to polish it up.
For the sanding, you can also use rol loc discs on a die grinder, they work awesome. They come in 3 standard grits, coarse, medium, and fine. For the shifter you could use the medium then fine rol loc pads, and then hit it with the buffing wheel.
You can polish this stuff without a buffing wheel if you want to grab a can of mothers polish and throw in a good bit of elbow grease, but the wheel on a grinder will give you the best results. :beer: