Hi Whoosh777,
"another external way is from the commandline one can change papersize via eg -sPAPERSIZE=a4"
I tried this, but for some strange reason it didn't work with FW's output. Then I tried to find GS's init.ps file because I read somewhere about two weeks ago that you could use it to change the default paper size. I didn't think much of it at the time, so I can't remember where I saw such a suggestion.