There is a section of the SourceGear forum dedicated to the Vault Client API which can be found here: DEVELOPMENT TIPS. In there you will find many examples and questions that have been answered.
The documentation for the Client API is found in the Vault client API download.
Client API documentation, examples, and questions
Moderator: SourceGear
Client API documentation, examples, and questions
Beth Kieler
SourceGear Technical Support
SourceGear Technical Support