I know a lot of people would love to have this feature and Cisco's TSP driver works only with 3.x versions of Callmanager. I am not promoting this product that I am going to talk about today, but I found it to work flawlessly (except a few crashes that i got initially). The Outlook Dialer is from Netelligent.
The executable is free for download and you can also register for a free license. The product is free for use if you can live with the popups about Netelligent products once in a while, or when you start up Outlook.
A readme doc with installation instructions is provided with the download. It explains with screenshots, step by step instructions on setting up Outlook.
Once the installation is complete, you have to go to Tools->Options->Unified IP Outlook Dialer tab and configure the following,
a. Callmanager IP address
b. Callmanager userid (end user)
c. Callmanager userpwd (end user pwd)
You will able to use the Lookup button to find all devices that are associated to you and also select the line using which you want to place calls.
Once these settings are configured, you may need to restart Outlook to prevent some of the crashes that i got and Outlook was not responding very much after that.
After the restart, You can dial from Contact books directly. Works great.
Hope this helps.