Bill (Willard) Anderson and Joshua have put out a very good video on this subject.
I have tuned a few molding planes and most of them had edges that had been rather abused over time. I normally had to slightly reshape the blade prior to sharpening them. I start by getting the backs flat and honed then reshaping the profile, if necessary, using a rotary tool and stones. Not the traditional method, I know, but it works for me. Unlike Mr. Anderson, I normally just sight along the plane sole with the blade and wedge in place to determine where the profile needs to be reshaped. After the shape looks correct I use both stones and sandpaper on dowels to actually sharpen the bevel edges. After that I use dowels charged with honing compound or cotton wheels and a rotary tool to polish the bevel, being careful to avoid rounding the edge. If the plane cuts well then the work is done. If it doesn’t then I diagnose the flaw and work it out. After the initial tuning they normally only require a touch with a fine stone and maybe a little honing. One of the cool things about woodworking is that there is normally at least three ways to get the job done. The trick is to find what works best for you and your situation. Just because someone does it differently does not make it wrong, just different.