3m kit does a similar job^ worked good for me.

What I would do is mask off the section that you want to work on first as you don't have a line on which area you want Defluted. Once you have done that I would removed the rest of the ribs. A dremel would work if you are in a rush but personally I would use some 120gr. sandpaper and carefully sand away the ribs. Once you have sanded away all the ribs down you want to get the whole surface smooth I would use a 320 then progressively work your way up to a finer grit as you go.

It can be done just takes a long time! I did this to a pair of headlamps myself and it took a good 8hrs to get it done right.