Not as elegant as a pasted in list, but perhaps one option would be to modify your .ssi file directly. Of course, we highly recommend making a backup of your .ssi first just in case. With that done, we can do the following:
Create a new export job in Lighthouse Studio with a unique name. Give it a field or two to export.
Open up the .ssi in a text editor (e.g., Notepad) and perform a search for your job name. Not far from that name you should be able to find an excerpt to this effect:
That first number is the number of fields we selected for the job in Lighthouse Studio, and the remaining lines are the names of those fields. From here, we can adjust the first number and paste in whatever fields we want exported.
When we open up the modified .ssi in Lighthouse Studio, we should find our export job has been changed accordingly.