I have thus been unsuccessful in getting 120hz on my tv. I think it is a firmware issue that seiki plans on updating on an indefinate "soon". The 50 inch model does get true 120hz though.
I am just glad to get 1440p at 60hz out of the thing. The TV properly recognizes it once the EDID is forced to it via Toasty's CRU. There just seems to not be any way to get the TV to cooperate in any kind of 120hz at over 720p.