The skirt shown here is the default Pleated Skirt (included among the SDT.swf assets), as is the necktie collar. Both will be activated automatically (via embedded charcode) when the mod is loaded.
The shirt can be recolored via the Top.RGB sliders. This change will not automatically apply to the skirt; you must update the skirt via the Bottoms.RGB slider if you want both halves to match. The necktie can be recolored via the Collar sliders.
The apron is just plain-old white. It will not respond to RGB sliders.