The N73 (or any mobile phone that I know of) doesn't have a high enough screen resolution for playing the Broken Sword games, and thus it is not supported for the Symbian ScummVM.
Check here for a Symbian compatability chart:
http://wiki.scummvm.org/index.php/SymbianOS_S60
I was dissapointed too, as the only reason I bought my N73(my first Symbiam phone) was to play the BS games on it. That's what i get for not doing my research properly first.
Anyway there are so many other fantastic games that, I have not played for years, availble that it doesn't matter too much.
I just hope that the screen resolution on a mobile phone will soon be high enough that the BS games can be scaled to it.