Here's some
pictures of 'Lifeliner 1' which sits on the roof of the VU Hospital in Amsterdam, the Netherlands. The helicopter is either wheeled or flown (I don't know which) onto the dolly, which rides on tracks into the hangar. Recently, the vendor ANWB (the Dutch version of the AAA) has switched to the EC135 and this setup has been modified/beefed up to handle the increased aircraft weight and/or dimensions. If you're really interested I could put you in touch with one of the pilots there. I'm sure they can give you all the details of their setup