function myStruct(a)
{
    this.myAttrib = a;
    this.myMethod = function(d)
    {
        var tmp = this.myAttrib;
        this.myAttrib += d;
        return tmp;
    };
}

var t1 = new myStruct(1);

WScript.Echo(t1.myAttrib);
WScript.Echo(t1.myMethod(1));
WScript.Echo(t1.myAttrib);