Starting from CVI 6.0 there is a feature to transform panels into source code (Tools >> UI to Code converter).
By this feature, you don't need the .UIR file any more, because in your code is automatically created the lines necessary to create and disply the panel you designed in the uir editor.
If you have a version since 5.5 inclusive, this feature is unavailable, but all the functions needed are (NewPanel, SetPanelAttribute, NewCtrl, SetCtrlAttribute), and this work can be done manually by yourself. I assume a panel to ask a password can be slightly simple, so the work shouldn't be too much even in this case.
Hope that helps.
Roberto