Sure. Use cyberduck (OSX) or WinSCP (Windows) and SSH into your
Copy the file email@example.com and edit it in photoshop or any pic editing app you are familiar with. It's a transparent texture file. What I did was I filled it with color put a smudge stick filter and then lower the opacity to give it a more transparent look and then saved it locally on my hd. I replaced the one on the iphone folder then I deleted the cache files in this folder /private/var/mobile/Library/Caches/bsbg-*.png. Then respring
Repeat changing until you get the proper look you want.