Notemapper
http://www.vst4free.com/free_vst.php?pl...mp;id=2169

seams to be nice. And of cause Max for Live offers everythink:
http://www.maxforlive.com/library/devic...ote-mapper

It is so great, that Pianoteq has pernote-editing including Microtuning. I think, it would be easy to include
a notemapper, too.

I mean a software arpeggiator like these : http://www.hitsquad.com/smm/tags/arpeggiator/

1)  . . . host Pianoteq in a sequencing/synth ap/program for example, Logic. 

2)  . . . set your chosen Pianoteq preset to have a minimum polyphony such as 2 or 3

3) . . . chose your synth preset from the host ap/program with polyphony of 12 or more

Either my suggestion AND any other way that might be technically more to your liking would require a carefully executed playing technique.  To be thinking about these type of things is akin to the automation organ manufacturers went through from early Lowrey Organ Co.'s AOC (Automatic Orchestra Control) of the 1960's up to present auto accompaniment technologies for playing in real time.  Layering tracks with state of the art synth devices is fine.  But keyboards that let you "sound like a pro" as you are playing in real time require that players actually know what they are doing in the first place!

Lanny