There are a number of resources that can help you get started in developing XML apps for the Cisco IP Phones.
Cisco Press has published a book on the subject:
"Developing Cisco IP Phone Services: A Cisco AVVID Solution".
You can either purchase this book at a local or online book store, or read it online at a service like Safari (http://safari.oreilly.com/). Safari allows a free 14-day trial period, so you could access the book's contents online right away if you'd like.
I would suggest joining Cisco's Developer support program to get access to updated SDK's and other information including many sample applications.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.