How to mouse click in pop-up window

[kokyo]

I "_IENavigate" a web, login and do something all are ok. After that, when I do a mouse click on a button by "_IEAction" function, there's a pop up window showed to ask me "conform" or "cancel". I don't know how to click the "conform" button becase the script is waiting for the pop up window. Is there any method to click it by script? Someone told me I can load the web first, re-write it don't show the pop-up window to replace the regular web, I have no idea how to do it though. Thanks a lot.