- Create a text file "foo.xml" on your local computer.
- Add some wrapper XML into that file that looks like:
<?xml version="1.0" encoding="UTF-8" ?>
<ModulePrefs title="Custom Gadget" />
//your stuff goes here!
- In your Google Site, upload the file as an attachment.
- On the Sites page in which you want your gadget to show, create a new gadget from a URL, where the URL is the location of your file. In other words, something like https://sites.google.com/a/domain.com/foo.xml
If you're really clever you'll quickly discover that building an interface to allow you to customize that gadget is also super simple.
But why bother if it's just for you? Do the simplest thing that possibly works if you want to ship!