Thanks to ideas from this forum and some of my corp mates, I've written a script that will trade down a list of pair ports. It's geared for high turn games, but I've been able to use it in low turn games by carefully editing the input file. Here are the directions for using it.


1. Install it to your scripts directory, modify SWATH.ini to include it.
2. In a game, run a CIM Download to update SWATH's db for all your known ports. (SWATH menu Commands\CIM Download)
3. Run the SWATH Port finder tool. (SWATH menu Tools\Port Finder). Select 'Port Pairs'. Select type of Ports you want to pair trade. I use XBS and XSB ports with min/max percentages of 75%/100%.
4. Click 'Copy to Clipboard' button to store the report in memory.
5. Run Notepad (or other text editor) and paste the Port Report into a new file. (Edit\Paste). Save it in the same place as your swath file for that game. The script expects the file name to be PairTrader-<gamename>.txt, but you can save it as anything and change it in the dialog box.
6. Run PairTrader in SWATH and enter the filename you saved, if you didnt save it as the default. 
7. Sit back and watch the SWATH Console tab for information as the script runs. 


If something stops the script (defensive figs, etc) you can safely start it again withhout having to update the input file again because the script will check each port before it moves to it and if it's already been traded down it will skip it.