Boeing has some artists' conceptions of their CEV system up on their website. Their ideas for a translunar insertion stage and resource module would be easily adapted for use in a Hubble rescue mission, if they can be developed in time. Their version sends a CEV from the earth to a lunar-orbit space station (which looks like it was put together with two launches) aboard a Delta IV rocket. The rocket can be configured to send either cargo or people, and can do so on fairly cheap boosters compared to Shuttle. Boeing has obviously had this idea in mind for a while. Good.