Hi there, I too decided the trash needed updating.
I replaced the png files, switched users to Root, weird thing was in the Dock Resources folder the Trash icons were still the old ones, also the Icon for the Dock app was different, it was the icon from Tiger, double weird.
Anyhow one reboot later and I have a new trash can!
Not sure what is going on here, I didn't change permissions to Root for either of the replaced png files.
I hope others have more luck.
Regards,
Anil.
Message was edited by: Anil K Solanki