The Yahoo! Connected TV Engine runs on the hardware of the specific CE device. In order for the YCTV Engine to work on other devices the engine would have to be integrated into that particular device. It could be integrated into a set-top-box but a STB with the YCTV Engine is not yet available. In regards to it working with a PAL 720X576 TV I would assume it would as long as the STB could connect to the TV with the appropriate connection but not 100% on that.
You would have to work with Yahoo! Connected TV to get it integrated/ported to another device. The YCTV Engine is not available to the public for distribution.