How to programmatically allow access to the KeyChain for my application?

Question

Need to avoid the conformation dialog.

Answer 1

The dialog box a security feature of the keychain. Because it stores sensitive user information, the OS takes the position that the user should always have the option to prevent the use of this information so that the user can trust they're not being used without their knowledge.

So no, there's no way to prevent the security dialog box from being shown. You can make your user's life easier if you code sign your application. When you update a signed app app, Mac OS X will recognize that it's the same app and won't prompt your user again if they've decided to always allow access to their credentials.