Are you guys sure that 542 is the NHL Network, or could it be another NHL Center Ice channel? If it were NHL Network, why don't they just map it to 403 and/or 559?
I believe the Sabres games are set up on the ALT sports channels that are in the 435-445 range. I don't know if they would show up yet on the program guide. 412 is MSG for the Rangers.
If I remember correctly last season during the playoffs on Thursday and Friday nights there was no HD hockey because Versus dedicated their HD coverage to golf.