Adding Event Listener As Attribute Breaks?

I am testing some code that finds and element and attempts to add an event handler attribute to it as 'onclick' (test case in Firefox 3.5.9)

/*
The actual code is:
window.onload = function()
{
//<irrelevant code>
var test = document.getElementById('tstEl');

[Code]...

I am trying to do this because Element.addEventListener or Element.attachEvent won't allow for arguments to be passed to the event handler code/function. What is going on here? The only line referenced, line35, in the document text containing javascript code is irrelevant to the problem.