bindify.js

var obj = {
  prop: 'foo',
  method1: function(){ return this.prop; }
};

obj.method2 = function(){ return this.method1(); };

function bindify( obj, name, fn ) {
  obj[ name ] = function(){
    return fn.apply( obj, arguments );
  };
};

bindify( obj, 'method3', function(){ return this.method1(); } );

var method1 = obj.method1;
var method2 = obj.method2;
var method3 = obj.method3;

console.log( obj.prop );      // "foo"
console.log( obj.method1() ); // "foo"
console.log( obj.method2() ); // "foo"
console.log( obj.method3() ); // "foo"
console.log( method1() );     // undefined
console.log( method2() );     // undefined
console.log( method3() );     // "foo"