A device that converts HDMI to 1394 would be:
1) a little pricey as it would require a real time HD compression encoder
2) lower quality due to the compression required to make the video fit into 1394's relatively limited bandwidth. HDTV resolutions (720p/1080i) require about 2.2Gbps for uncompressed video, while 1080p requires twice that amount.
The final issue would be that it's not clear what type of compression format your TV supports for the 1394 input: MPEG2, DV, etc? I had once heard that your TV manufacturer might offer the ability to upgrade their 1394-equipped TVs with DVI HDCP or HDMI input hardware- it's worth checking to see if this is the case.