"Here is how to manually Upload New SummerBoard Themes that you find online:
Install OpenSSH then install BSD Subsystem from Installer.app
Find your iPhone’s IP address: Go to the Home Screen > Settings > Wi-Fi > [Your Wi-Fi]. Look for the DHCP IP address. (Something like 192.168.1.10 etc.) This depends on the Wi-Fi network you are connected to at the time.
Disable Auto locking on your iPhone to make sure the device doesn’t fall sleep while you try to FTP to it. Settings > General > Auto-Lock > Never
Open up any FTP program (FileZilla for Windows, or CyberDuck for Mac) and create a new connection to your iPhone.
Host: [THE IP ADDRESS]
User: root
Password: (The default for versions 1.0.2 and earlier is dottie. Default for version 1.1.1 is alpine
Browse to the folder /private/var/root/Library/SummerBoard/Themes/ and upload the entire folder for the theme you have downloaded to the Themes folder on your iPhone.
Go to SummberBoard via the SMBPrefs button on the Home Screen. Go to Themes and you will see the Theme you just uploaded. Select it.
For best results make sure settings for Theme Wallpaper, Theme Status Bar, Theme Icons and Theme Dock are all set to ON.
Go back to your Home Screen. Voila! you will see the new Theme applied to your iPhone.
Get it via Installer.app or iBrickr"