Hey there.. no you can't use the TV Tuner Card slot as it's not a SATA port.. you only have one MSATA port on the Motherboard. Refer to the Dell XPS One 2710 manual it actually has a diagram of the Mobo and shows where the MSATA slot is located.. only one.
YES it's possible to have the system boot from the MSATA as long as you have Caching disabled (Intel Rapid Storage software) Accelerate and you've disabled Raid in the BIOS.. once you do those two things you should see the MSATA as a regular Drive.. then install your OS to that drive.