After trying many different suggestions to get my iPhone 3g enabled for iCloud syncing of contacts, this post provided the most hope. With a little additional clarification, I was able to get my contacts to sync. Here are the steps:
1. Open the following file in your favorite text editor: ~/Library/Application Support/AddressBook/Sources/7921EFBD-B836-46B8-8B0E-BF7CC58FE7FD/Configuration. plist keeping in mind that the cryptic name after /Sources/ may be different. It was necessary to use this file b/c in my case my Mac Addressbook has local "On My Mac" contacts disabled b/c it is using iCloud. This means that he file suggested by Kyle67 was not pertinent.
2. In that file locate an XML block that looks similiar to the following snippet. You are seeking the CARDDAV URL for your iCloud .vcf file
<key>homeInfo</key>
<dict>
<key>/194117440/carddavhome/</key>
<dict>
<key>me-card</key>
<string>https://xxxxx%40xxxxx@p02-contacts.icloud.com:443/194117440/carddavhome/card/Qzg 2RDIyNjgtNTM1MC00NkIyLThCNzgtMzI3MEYyMTk1REE5.vcf//xxxxx%40xxxxx@p02-contacts.icloud.com:443/194117440/carddavhome/card/Qzg2RDIyNjgtNTM1MC00NkIyLThCNzgtMzI3MEYyMTk1REE5 .vcf</string>
3. Copy the entire contents of the URL between the <string></string> tags into your clipboard.
4. Paste this URL into an email and send yourself an email to any account available on your 3g phone. Open the email on your iPhone, click the Forward or Reply icons so that you can go into the editor and select the entire URL into your iPhone clipboard. This saves alot of time, avoids errors and painful typing :-)
5. Now on the 3g open Settings/Mail,Contacts,Calendars and create a new CARDDAV account. Paste your URL into the Server name field and supply your iCloud credentials.
6. You will need to wait a few minutes for your AddressBook to get primed via iCloud but all should be fine.
I want to thank Kyle67 b/c many of the prior methods for enabling CARDDAV always resulted in a SSL error during setup of the account.