Sdl_mixer

Hi
I am Playing with SDL_Mixer, i am all my sound effects as mono 8bit
wavs to keep them small, I am not a beginner as i have already done
one game with SDL using SDL_Mixer, but i want to do more with the
sound in this game so, how do i use Mix_SetPosition? and what can i do
in my Mix_SetPostMix call back?

Also does anyone have any nice code snippets of some fancy stuff to do
with SDL_Mixer?

Trish x