We've posted a new article on how to call FileMaker scripts from "webviewer portals". We use webviewers instead of portals in products like SQLexporer so folks can change the column width and resize the portal columns easily:
All the example code is in the free, and unlocked, SQLexplorer if you'd like to add stuff like this to your own solutions. Big thanks to Jason Young for putting this together and sharing it.
Hope you find it useful,