I've already tried to find out more information on the IPTV function on these forums before, but without much success. But as it stands at the moment I don't think you can.
I was hoping it could be used with Homechoice instead of the STB which only has scart connectors.
I emailed Kiss, and they replied that it is scheduled for a future FW release but didn't seem that informative. Snazio too advertises the IPTV function, but again no one knows much regarding it.
All these 2nd generation media players use the same chipset, so
AFAIK see no reason why they all couldn't stream IPTV with relevant FW.
The problem is that this is a very "niche" technology at the moment. Eventually this will probably be the way everything will head, but Homechoice is one of the only VOD providers in the UK (first in the world to use Mpeg4 compression) along with SKY dipping their toes in the water.
But until BT can get off their arses and start upgrading exchanges, we will be limited in the UK and IMO won't take off until we have a decent infrastucture installed (minimum 10 mb/s) for Internet/HD TV streaming etc.