need some convolution application advice

[Bill Washburn]

After a number of years, I have recently become aware of convolution. I
currently have a plug-in called SIR2, and I think I understand the basics,
but I need to go further. There are several musical instruments that have a
certain characteristic within a mix that I want to imitate and use in a
different mix. It was quite impossible to imitate the modified instruments
because of lack of availability of equipment, orchestra, etc and someone
suggested convolution. To my surprise, using a short sample of the original
mix as a wave file and loaded into SIR2, when I load my dry instrument into
the keyboard, I get a sound very similar to that in the original mix.
However, here is what I need to do: there are probably six or seven unique
instruments within the original mix, all with slightly different
characteristics. Is there any way to imitate each instrument separately,
using convolution, so I can mix them later? In my brief experiments so far
with SIR2, I'm finding that input instruments seem only resonant on certain
keys that correspond with the convlution sample. So I'm thinking of
separating the sample mix as best as I can, using brickwall filtration, and
then using each sample separately as I input from the keyboard. Just keep
in mind that I'm *not* trying to use a broadband reverb sample in SIR 2; I'm
using an actual short sample of a song as a convolution file.

I welcome any suggestions in this matter or any links to more in depth
tutorials on convolution.

Thank you,
Bill