A HD DVD is set up quite differently from a Blu Ray disk. In fact it looks more like a DVD only it has a HDDVD_TS folder as opposed to a VIDEO_TS folder and it uses EVO files instead of VOB files.
HD DVD is capable of reading AVC files but as far as I know though, the various programs that went out prior to the HD DVD demise only covered HD DVD creation in a mpeg2 format. I don't remember them ever getting as far as AVC creation before they shut it down.
I don't know if the newer version of Pinnacle studio (14) still does HD DVD but if you can get ahold of studio 11 it will do it.... as well as the older version of Ulead movie factory.... version 5 I think it was. Either way, i believe you will be forced to convert the avchd over to mpeg2 before disk authoring.
For what it's worth though, you should consider getting rid of the toshiba and going with blu ray. You can't get the toshiba players serviced anymore (I have the toshiba A1 so I know) and to do these disks in a HD DVD format is a bit risky.
