Syntax for FrontEndSelectionSetStyle

I know FrontEndSelectionSetStyle is undocumented, but its name suggests it does what I need. What is its syntax?

I have already tried several variations of the following button on some selected code in an input cell.

Button["set",
FrontEndSelectionSetStyle[FontColor, RGBColor[{1, 0, 0}]];
Print[CurrentValue["SelectionData"]]]


Update

Using the kernel, the following code does what I need:

Button["set",
SetOptions[NotebookSelection[InputNotebook[]], FontColor -> RGBColor[{0, .7, .5}]];
Print[CurrentValue["SelectionData"]]]


I assume that FrontEndSelectionSetStyle can change the font color of the selection while using the front end only. If so, what is its syntax?

-
After your update it is unclear what your question is. Can "what" be done in the front end only? –  Mike Honeychurch Oct 18 '13 at 20:42
@MikeHoneychurch: I re-worded the question, thank you for the note. –  Hector Oct 18 '13 at 22:12