Change folder icons in Mail

Howdy
I set up my Gmail IMAP account in Mail, and found that it just uses boring folder icons for my Inbox, Sent, Spam, Drafts, etc. folders.
Is it possible to change these icons to the nicer icons used up in the "Mailboxes" section of Mail?

Screenie:


Thanks.

Thanks, but that changes just the folder icons for the system. I can't change each individual icon there at all?
You can't Get Info and one individual folder so you can't do it how you would normally. Are those folders also normal folder found elsewhere?

Okay, I thought I got it but I guess I didn't.
I went to Users > {Me} > Library > Mail > {Email account}
Some mailboxes are in there, others are in a folder called [Gmail]
So I Get Info and replace the icon as usual.
Unfortunately that does nothing. If anybody has any idea on how this can be done I'd like to know. Otherwise I'll; keep trying. I'm sure it's possible.
EDIT: It appears a .mailbox file is just a folder. There are two folders - Messages and Attachments (I'm sure you can guess what's in them!) and a plist. I have changed the icons using the Get Info method on all the folders and it doesn't do anything.