For instance if the style is table how should the user provide the colors? as a semicolon seperated string?

"Colors"? The foreground and background colors need to be the same or there is no point so the user only specifies one color, in whatever format their browser supports. So they could say "white" or "black" or "#cccc33" or whatever.

Likewise the text for the link and div and table modes, where would it go in the template?

Just provide one value to be optionally overridden and if they want to override other parts, then they can edit the resulting values (as I mentioned).