HOW TO SET Global "CMD OPTION N" = new firefox browser WINDOW on mac 10.6x??

hello: I would like CMD OPTION N - to always open a NEW firefox window no matter what app I am in. or if frefox open or not.

currently, to get a new window, i have to click the fiefox in my dock select new window i prefer 1 global hot key.

is this possible? if so how?