I normally use TextFormat objects to decorate text. TextFields properties really aren't suited for it.
First you have to create a new instance of your font, then assign it to the .font property of a new text format.
I would change the linkage class name to proper class name format like Arial and ArialBold
Then create the instances
Actionscript Code:
var _arial = new Arial();
var _arialBold = new ArialBold();
Then create the textformats:
Actionscript Code:
var arialFormat:TextFormat = new TextFormat();
arialFormat.font = _arial.fontName;
]var arialBoldFormat:TextFormat = new TextFormat();
arialBoldFormat.font = _arialBold.fontName;
Then assign them to text fields
Actionscript Code:
myTextField:TextField = new TextField();
myTextField.text = "Some Text";
myTextField.defaultTextFormat = arialFormat;