The details below are still somewhat correct but the process is now as simple as download and installing the software.
Example of Dot Completion

Example of Intellisense Completion

Setup Instructions
To make this work do the following:
- Make sure you are running the latest version of Zeus found here: http://www.zeusedit.com/download.html
- Start Zeus and use the Options, Document Types menu to edit the Go document type, selecting the Triggers panel
- Use the go_intellisense.py script for Dot Autocomplete
- Use the go_intellisense.py script for Brace Autocomplete
- Use the go_intellisense.py script for Autocomplete
- Use the go_goto_definition.py script for Goto Definition
- Use the go_declaration.py script for Goto Declaration
- Edit some Go code and you should see intellisense on the dot key, the open bracket key and the Ctrl+Space key and goto declaration, goto defenition menus.
Go Language Tutorial
Zeus + goimports