Dynamically targeting properties of an object

Hi there, I have an object that has properties that are numbered numerically but I cant seem to access them dynamically. Can anyone help?
Thanks!

[AS]var myObj:Object = new Object()
myObj.p1 = 100;
myObj.p2 = 200;
myObj.p3 = 300;
for (i=1; i<4; i++){
tmp = [“myObj”][“p”+i]
trace(tmp)
}
[/AS]