It is possible to do some of what you ask, although a lot of work I think and also you would run out of wave memory after installing about 19 or so - even assuming you had installed the supplementary DIMMS of 1Gb.
The method for the question asked would involve creating a 1 element custom voice for each wave. Method is given in the Ty3 reference manual starting page 17, downloadable from here:
http://www.yamaha.co.jp/manual/english/index.php

Bear in mind there is only space allocation for up to 128 custom voices in TY3 as well as the need to install a max. of 1Gb of DIMMS for wave memory beyond about 4Mb.

It may be possible to simplify the job and still get the quality you want by reducing the number of .wav files and voices you use but spread each over a number of notes rather than keep to one wav. per note. In fact the method suggests this as the norm. You may want to experiment to see what you can "get away" with. Simplification is in any case necessary because of the memory requirement.

Sorry I can't help any more than try to point you in the direction- I haven't attempted this myself
John

[This message has been edited by jwyvern (edited 01-03-2009).]