it is possible to put in your own custom chord but if you want the player to play it, you have to use the ones in the chord quality list as these are the only ones it knows how to play. So you can get an error when press Play, but it will still play the rest of the chart.
Usually the # comes before the 5 as in Dm9#5. What do you mean by editing? do you use apps like Pro Chords for ipod, ipad and iphone? They might help. Are you playing an instrument--guitar or piano? What do you need to do?