There is an older version of YAST with ncurses "GUI" but I don't know whether it is still part of the standard distribution (YAST2 is the currend version). You might try to find a version where YAST(without version number) is still included and update that installation later.
Did you try the <tab> keys to jump to the necessary buttons? (Or <ctrl><tab> or the arrows or whatever)?
I doubt that this is a resolution thing (gut feeling
) but I don't know of a way to change the xorg.conf while it is not even installed...