How to add customized window during installation

Hey guys,
We are trying to implement a policy statement during installation. During symbian installation, I want to add one dialog to confirm capablities we are going to use in the application, if user agrees, installation will proceed, otherwise stop installation. I saw one of symbian signed application does that, is there anyone know how to do it?

Thanks in advance.

See the "Package file format" documentation/examles in the SDK.

Example excerpt:[quote];Display 2 options to the user
!({"Option1","Option1"},{"Option2","Option2"})
if option1
"files\option1.txt"-"!:\private\10000005\import\InstTest\option1.txt";
endif
if option2
"files\option2.txt"-"!:\private\10000005\import\InstTest\option2.txt";
endif

;Some text files to display in dialogs during the installation. These files are not installed.
;'TC' continues with the installation after displaying the dialog.
;'TA' presents the user with an option to abort the installation.
"text\textfilec.txt"-"", FT, TC
"text\textfilea.txt"-"", FT, TA[/quote]

Thanks so much, it really help