Unfortunately I'm playing a Casio Privia right now (yamaha c3 is at my parents' until me and my little family find a bigger place!), so I don't have a sostenuto...although I think they make one if you have the console stand...in any case, the notes I can think of right now are as follows:
I'm sorry but I have the IMC edition with no measures, so I'll use reference points and count from there.
I. Allegro inquieto
in the Andantino theme starting with the *first* measure of 9/8, in the second measure you must hold an octave of A- and AA-, likewise in the 8th measure. Then in the 14th measure BB-. And you will easily see this happens several more times as well as in the recapitulation of the Andantino.
II. Andante caloroso
Measure 14 introduces a common bass motif in the piece. I know some of these guys' hands were large, but surely not that large! There are a bunch of pedal-tone bass notes that must be abandoned for other left-hand stuff as well.
As far as the IIIrd movement Precipitato, it doesn't have time for such things...but what a beauty, god I love it.