[AS2] How do I Create Object-Orientated Functions?

[Vadersapien]

I'm guessing "missile" is a previously created object, right?

EDIT: What about doing something like this(javascript)

cat.prototype.changeName = function(name) {
    this.name = name;
}

firstCat = new cat("pursur")
firstCat.changeName("Bill")
firstCat.talk() //alerts "Bill says meeow!" 

in Actionscript?