if you want piano, the best bet is to get a guitar synth. the best you can hope for from the axe is old skool moog stuff, squelchy basses, analog strings etc etc. stuff based on simple waveforms. piano is too harmonically complex.
here are some examples of what you can do with it...
there are loads more possibilities...square wave leads, moog taurus pedals, even some horn type stuff, but sounds which are typically sample-based, like pianos etc just aren't possible. i've asked for the ability for one synth voice to modulate another, so we can get into some FM synthesis, but i don't know if it'll ever happen...