This poses some problems... I'm pretty certain that the Myth that ships with lmce-0704 will not work "out of the box" with DVB-T trasnmissions in H264 (I might be wrong about that though).
We are working with the lmce-0710 Dev team to add VDR to 0710 as we speak but as it stands VDR does not support H264 encoding without the use of a plugin and that plugin will not be in the initial 0710 release. Its possible that is could be added later but I cant say how soon that would be at present.
This is my understanding also. When I tested DVB-T, I did not use MythTV (had some problems with identifying the HVR-4000 card, but it was some time ago so I don't remember exactly...). (I used the dvb-utils programs: dvbscan, dvbsnoop, dvbstream)
Part of the problem is that the h264 is not identified in the received stream as a video stream, instead it is marked as "other" (I'm located in Norway, don't know if this is true for NZ). So the scan utility does not correctly identify the streams carrying the video(or the audio for that matter). I suppose MythTV/VDR/other tools might be the same. To get anything at all, I had to manually find the correct stream PID's and add them to the tzap/channes.conf file.