Custom dock image - how to find out the exact position of the icons?

Hi,

I'm working on a custom dock background, and I want to add reflection.
I'd like to use the standard icons for phone, safari, mail and ipod.
But how do I find out the exact position of those icons in order to add reflection correctly?

Thanks in advance!

Use an already created dock image that has reflections as a reference?

Thanks for the tip, I did that.
But there's one more problem I've got.
I can't get the iPod icon from the iPhone in its original color. On my mac, it is blue.
But I need it in the correct color to create the reflection.