createEventObject, attachEvent, How to pass keyCode to event.

I am automating the IE DOM for webpage automation. Within one page is a JS function that looks for an events keycode, and if it was "Tab" then it will create some lines within the webpage. I cannot use "SendKeys" to do this.

Currently I have code to do the following;

set eventObj = oIE.Document.createEventObject()
eventObj.keyCode=9

Then I execute the following;

oItem.ID.fireEvent "onkeyup", eventObj

This does not seem to work. Any ideas?
Do I need to use, attachEvent and getRef ??

TIA.