Textbox.text on frame before textbox exsists

I have some button code on frame one. that looks like this:
[AS]on (release, keyPress “<Enter>”) {
mylogin = new LoadVars();
mylogin.password = password;
mylogin.username = username;
mylogin.sendAndLoad(“page.php”, mylogin, “POST”);
mylogin.onLoad = function() {
textbox.text = mylogin.message; //<–here
gotoAndStop(5);
}
}[/AS]

basically sending and recieving variables from a php page. I want to be able to specify what my textbox on frame 5 says in the onLoad statement. Is this possible?

Currently the only way I have been able to get the text to display is either to use the textbox variable and declare that in the onload statement, or to put textbox.text = mylogin.message;
on the actual frame.

I doubt there is a way to do it, because the actual textbox hasn’t be created yet, but if there were a way, that would be nice.