This is how to add text leading using Actionscript 2 for Flash.
[code lang=”actionscript”]
var txtFormat:TextFormat = new TextFormat();
txtFormat.leading = 5; // change this to whatever you need it to be
ttt.setTextFormat(txtFormat);
ttt2.setTextFormat(txtFormat);
[/code]
There is also a GUI way of doing this:

Select your textfield and and under the paragraph section, set the top/right hand icon (Line Spacing) to whatever you like.