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This guide assumes you have a jailbroken 1.1.1 iPhone with SSH and BSD up and running. You will also need to apply Springpatch to your SpringBoard. If you're not up to speed, follow these guides:

Dev Team Jailbreak 1.1.1 from 1.0.2 Windows

Dev Team Installing SSH 1.1.1 Windows

Dev Team Install BSD World 1.1.1 Windows

Dev Team Install Springpatch 1.1.1 Windows

This method of adding an icon to your homescreen can be applied to any third-party app you might have manually installed as well. You simply need to change the text you will be copying between <string> and </string> to match the identifier for the desired app. This can usually be found in the Info.plist within each application's own directory.

If you use Nullriver's AppTapp Installer.app, you can add third-party apps to your iPhone directly over its internal WiFi or Edge connection. Applications installed with this method generally add their icons to the homescreen automatically. If you haven't already installed AppTapp Installer, a guide can be found here:

Dev Team Install AppTapp Installer 1.1.1 Windows

Step 1

Download and open WinSCP: Available here!

Connect to your iPhone.

IP Address: Check your current WiFi settings on your iPhone.
(If you have trouble, try issuing a static IP.)
Login Name: root
Password: alpine
Connection Type: SCP
Port: 22

Step 2

Browse to /System/Library/CoreServices/SpringBoard.app/ and download the file M68AP.plist to anywhere.

Now, follow this link: Convert Apple property List from binary to text XML

Use the form to browse to your recently downloaded M68AP.plist. Once the full path to your M68AP.plist is in the textbox, hit the convert button.

A save file window should appear; save the file to wherever you like.

Note: If you recieve a mismatch error, that is okay, it just means your file has already been converted. Proceed as normal.

Step 3

Open the recently converted M68AP.plist in a text editor (WordPad, NotePad) and find the following lines:

			<dict>
				<key>displayIdentifier</key>
				<string>com.apple.MobileStore</string>
			</dict>

Replace this text with the following text:

			<dict>
				<key>displayIdentifier</key>
				<string>com.apple.MobileAddressBook</string>
			</dict>
			<dict>
				<key>displayIdentifier</key>
				<string>com.apple.MobileStore</string>
			</dict>

Note: If you look closely, you aren't actually modifying any text here, just adding a bit before the MobileStore part.

Step 4

Once finished, save your M68AP.plist file and upload it to /System/Library/CoreServices/SpringBoard.app/ on your iPhone using WinSCP (you may want to rename the M68AP.plist on your phone to something like M68AP.plist.bak as a backup file just in case anything goes wrong).

Congratulations!

Simply reset your iPhone and the Contacts Application icon should appear on your homescreen!