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Cut a 1" diameter dowel into 3" long pieces (or whatever
projection you would like for your knob).  Dowels can be found at hardware stores and come in lengths of 36".  Paint your dowel pieces to match your knobs.  You will also need a double-sided screw (or dowel screw).
Drill a small hole in the center of each end of the dowel piece.  Insert the double-sided screw into one end and screw the knob into the other end.
To install, drill a small hole in the sheetrock for the plastic plug wall anchors.
Gently hammer the plastic plug into the wall.
Screw the knob assembly into the hole.
Now your knob will have a clearance of about 3".  This technique is great for holding light- to medium-weight valances that do not require a lot of support.  If you  would like to skip all these steps, you can buy our post adapter/extender.