Dont know any site but from experience we used sand as padding for the outriggers of a 500T crane used to lift a load of 60tons.Althought the crane was situated on a roadway this is just an example which may be of use to you. Check underground services before deciding best location for lift.
You could try STRUCAD which is a relatively new structural steel software package which my company has recently employed for designing structural steel and is also very useful for designing the connections required
Hope this helps
