Theres no way you can extand the fatality time. Only addicted Mk fans can easly do the fatalities in such short time. btw that is why i didnt buy a gamecube. Because of the fucked up controller.

Buffer the fatality button press during a jump or something like that, like say you win with a certain attack that leaves you a jump away, jump forward and do the motion in the air and as soon as you land hit the last button. When I'm in a fatality mood in UMK3 and say I'm Kitana, I'll be them with an uppercut or a fan throw or something that will put distance between us, I'll do her square wave punch across the screen, as she flies I time R, R, BL, BL, and when I land I press HK.