the installer should ask for and set the SYSDBA password. all good databases do this.
please don't leave the sysadmin to hunt for more instructions on how to properly install the database.
make it easier when you can.
Show the default database port in the port number textbox during installation when asking the user which port to install the server on. (when I installed mine, I had absolutely no clue as to what port the server was going to serve on by default, so I didn't know if the default would conflict with any other ports I currently had, and this was a source of consternation)
Auto-it3 is a scripting language like VB except that it basically works with one dialog. it has ShellExecute and ShellExecuteWait functions. If your gsec program gets fixed properly, it is possible to use a very simple 20-to-30-line program to call gsec to change the SYSDBA password.
I suggest having a "cancel" button, a "change password" button, a static text that says "userid: SYSDBA", and a static text that says "password" next to the password.
Leave some obvious space between the two static texts, but keep the two password items close together.
I might be able to write the code for you if you get gsec working and the command-line parameters for modifying users don't change (currently the command does not work).