WIP When in the editor, use the arrow keys to move the selector around, press space to select an object, and then choose from a list of id's here: http://pastebin.com/tq8LiNaW When you are done with your level, press 'e'. (Not working. Currently, and hopefully, being resolved on the forums here. https://scratch.mit.edu/discuss/topic/152142)
For the export level id script I used the save to list example on the wiki. http://wiki.scratch.mit.edu/wiki/Saving_Data#Saving_Data_with_Encryption