USB 3.0 Card on a 2008 Mac Pro running Yosemite 10.10
(Just wanting to close the loop on this topic since it's an old question without a definitive answer)

The chip for the device referenced by the OP - D720200AF1 - has long since been EOL'd by the manufacturer.  There have been some references to "hacks" to get this to work, but ultimately, they are unreliable because a device driver is more than just support for a particular chipset.  Ultimately, no native driver exists for card in question.

That said, to get USB 3.0 on a Mac Pro (2008 through 2012 models), Inatek makes a very good 4 port USB 3.0 PCIe adapter card.  Their specifications state that it works with Yosemite and above and I can confirm that it works with El Capitan (it also works with Windows XP through 10).