Event Handlers, OO And Function Context

I am writing a javascript code that parses dom and finds event
handlers attached to mouseover events. Then i will replace the
existing handler say B() with my own function say A(). When the event
happen and control comes to my function A(), after doing required
processing i will call B() as shown below

<a href = "abc.com" mouseover = "B();"link </a>

while parsing i will have (trimmed down version)

var oldHandler = node.onmouseover;
node.

function A()
{
/ * my code */
oldHandler.call(this);
}

This was working fine as long as B() was a global function. I started
getting problems when B was a member function. For eg:

function Alerter(text)
{
this.text=text;
var me=this;
this.invoke=function ()
{
alert(this.text);
}
}
var sayHi = new Alerter('Hello, world!');

The web developer would have code like
<a href = "abc.com" mouseover = "sayHi.invoke()"link </a>

But this time around, my function A() fails since although i have
handler to sayHi.invoke(), it has to be executed in correct context.
Other wise "this.text" is giving me error because when i say
oldHandler.call(this), i am executing the sayHi.invoke() with the html
element being passed as this.