I don't know if i've the time or if you you have too hurry, anyway i cuold try to do something... but how have to be these chess pieces?
Simple, odd, minimalist? Tell me more... i don't promise nothing to you, but if i fuond the time...
EDIT: I realized only now (i'm not so smart in these days... too work...) that you want
transparet Bitmap!! Well this is something that i can't do for you, cause transparent Bitmaps don't exist, it's a programming problem!
The best i can do is drawing the figures and the masks you need, but you have to put more code in your program to call the API for the tranparent effect.
Look
here,
here and
here: you'll find three ways to do that!