with vimperator you can press ctrl+z to enable pass-through mode, therefore allowing you to use the gmail shortcut keys, press escape to go back to normal mode.
Thanks for the heads up. That is quite convenient, unfortunately I'm now using vimium. I'm reminded that in my vimperator days gmail wasn't a problem because the vi key bindings just worked everywhere. All this is moot considering I can just patch the plugins. I assume vimium either has a similar capability or that it can easily be added, but it does allow a web app to trap key strokes before by default (opposite of vimperator)