Binding Object Method To Event

I'm trying to build a Validation object, where you pass an object id and event name in the constructor. Then, you call an add_rule method to add validation rules. The constructor code looks something like:

function Validation(id, event, ...)
{
this.object = document.all[id];
this.event = event;
var obj = this.object;
obj[event] = this.validate;
}

So the actual validation function is dynamically bound to the appropriate event. The problem is that when the validate method is called, "this" no longer refers to the Validation object; it refers to the object to whose event it was bound. So, for instance, in the following code, the validate function's "this" refers to frmSubmit, not objValidate:

objValidate = new Validation ("frmSubmit", "onsubmit", ...);

Of course, I need to refer to the actual validation object's properties, but I can't figure out how. Any suggestions?