Shader clocks will automatically changed when you change core clocks. But not 1:1 - every 27 Mhz core clock the shader clock gets 54 Mhz up. There are some steps between where only the shader clock gets higher and the core clock will remain.
Sorry for my bad english, perhaps this graphic is a little bit better, read it from left to right.
Left: the core clock you set
Middle: resulting shader clock
Right: core clock the card will use
So its no matter if you set the core clock to 508 or 525 Mhz, for example. The card will run at 513 Mhz core clock and 1188 Mhz shader clock. So it donīt make sense to take steps between this numbers in the graphic because the clocks donīt change.
OCing shader and core clocks separated is (as far as I know) only possible with some BIOS tweaking and flashing.