A date can be transferred somewhat easily, using a modified blog mode, but being able to transfer the time like the example site you gave would be quite a bit harder (if possible at all). The calendar was never meant to be used as a reservation system... it was built (originally) to display rental properties availability. Now it has matured into more of an event calendar - still not a reservation system.
If you only needed to give the day for the reservation, I have already worked it out by using the blog mode. Let me know if this would interest you.
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