Can you paint glass with porcelain paint?

Yes, it is possible.

You will need to get to a good Craft/Art supply retailer and find the paints recommended for painting on glass and porcelain.

Next you must remove the knobs from the cabinet and clean them carefully to remove any traces of oils. Then paint away... the manufacturer will have instructions on the bottle for "setting" the paint. This usually requires baking them in an oven for a set time. Once this is done, just remount them and you have a whole new look.

NOTE, this works best if the knobs you currently have are white as most of the glass/porcelain paints I have found are not completely opaque, and multiple coats increase your chances of streaks or other flaws in the finish.