You're not going to be able to do anything THROUGH the XP-8 that will give you any sort of remote viewing.  You would need some sort of remote viewing 'appliance' for your thermostats, then you would just attach the XP-8 to it for control in the house.  Unfortunatley, your HVAC with 2-way is limited to Aprilaire for now.  Not sure if they make a remote access piece.

This is definitely in the realm of Homelogic or Control4 and is easily doable with both.  When RTI gets their version of X-panel out you'll have a lot more options...