It's the loading of the script into the Actions list that I want to automate, if possible.
Sorry, my initial post was a bit vague.
So, for example, let's say you have a ReaScript which generates new scripts itself (using Python's OS module).
Rather than pull up the Actions window and load the new script manually, it would be great if I could simply have Reaper fetch the script as soon as it's generated. (I could tell Reaper the filename to expect, so on second thoughts it wouldn't need to look for the "newest" file.)