You don't need to host the jQuery javascript in order to use a custom jQuery Theme. To use a custom theme, all you need to do is upload the theme to your skin directory (just the images directory and the css file) and then place a reference to the css file in the style.config for the skin.
In your layout.master, remove the jQueryuithemename property from the StyleSheetCombiner control and add IncludeJQueryUI="false".
HTH,
Joe D.