Probably, but I think it would have to be on the server side, rather than the client side. This could be done with a Firefox extension:
- Create XML files of ping lists
- Create a dialog that accepts a story number and which ping list
- One of:
- Knows how the POST works and submits the proper data (you can get this by watching the POST of any post you make)
- Browses to the page, finds the "post reply" button, clicks it, puts your ping list in the To:, writes some text, and submits
The reason Firefox would be easier than Perl is because all the authorization is already set if you use the cookies.