I updated the original plugin and set the Max Version to 10.* so it could be installed on Firefox 10 and lower.
Works like a charm. You can set which instance of scuttle you want to post bookmarks to in the preferences page.
To package the extension for installation, run the following command in the root directory:
zip -r scuttle-0.9.0-firefox+fl.xpi chrome chrome.manifest defaults install.rdf
If you just want to download and install the plug-in, there is no need to download the source and package the plugin yourself, just go to the download page and download the latest version: it works with all versions of firefox.
I added a keyboard shortcut (shift-control b) to pop up the “save bookmarks” window.