UniVerse has the AE editor to edit multivalues which doesn't seem to exist in D3. I figure I'll write my own little version of AE :)
After a few hours I have most of the functionality that I use working. Implementing exploding of values requires saving things onto a stack which I imagine would get wasteful as I need to store everything in memory.
The biggest thing missing is undo but I could just keep the last 10 versions of the program as these records are tiny.
Writing a line editor is very simple when I can ignore the difficult parts!