Actually Luke screams in one of the pre release empire strikes back trailers so Lucas or was that Kersh had considered it long before the special edition.
In the trailer it sounds like Hamill though and not the emperor actor Ian M.
This is the vivadli four seasons trailer i don't think is on the 2004 bonus disc, or even in the definitive laserdisc set. Its not even on the editdroid.
Very low quality versions on youtube and t'bone star wars site.