What I have done in the past, was for the local Hd channels. I added a HD processor on a unused channel and had it just pass through. What ever is off air for that preticurlar channel would just pass through. That way, customer would not need a settop box to recieve Local HDs if they had a HDTV. If I remember correctly, I believe you can fit 2 maybe 3 HD channels on a single EIA due to the bandwidth that is used. Unfortualy, I haven't got that far yet. This was done on a 650mhz system. I was able to perform this on channels 70, 71, 73 and 74. Other than that, that is all I can help you out with. Hope this helps.
This is CABL.com posting #340065. Tiny Link: cabl.co/mbAC5