Well, first of all grab your Monitor's manual and where they sync at the required resolution (KHz/Hz Positive/Negative etc settings).
Input those in the P96 settings and then TEST and as zipper said... Play for LONG time with arrow keys and Alt/Ctrl.
It's seriously a pain in the a$$ but after some time and if you're lucky... You're gonna be really happy!!!
That's how I done 1360x768 on my really old Mediator 1200 setup displaying on my old 23" LCD/TV

