You can export the profile with File > Export FFF Profile. I've personally found this to be more helpful for when I want to change something being assigned to materials/qualities. Example: viewtopic.php?f=8&t=5977&p=25950#p25947
For editing the scripts I've found it much easier to do so inside S3D's UI. The UI automatically inserts newline characters in the XML when you save the profile. This allows you to write readable code for your script in the UI and have it be saved in the less easy to read, but correct, format where the entire script is on a single line inside an XML tag.
So it depends on what you're hoping to achieve in an external editing program. But you can do both. You can edit your scripts in the UI, then save your profile and export it. Then make any other edits you wish and import the profile back into Simplify3D using File > Import FFF Profile.