[Embed(source='assets/CALIBRII.TTF', fontName='fontCalibri', fontStyle='italic', fontWeight='light', mimeType='application/x-font')]


textFormat = new TextFormat();
textFormat.color = 0xFFFFFF;
textFormat.font = "fontCalibri";
textFormat.size = 11;
		  
textField = new TextField();
textField.embedFonts = true;
textField.text = "Embeded Text";
textField.selectable = false;
textField.background = true;
textField.multiline = false;
textField.backgroundColor = 0x000000;
textField.setTextFormat(this.textFormat);

This describes how to embed font in to Flex(mxml) file without using the <mx:style> tag (fully AS3).

Embedding fonts in AS3 on Flex 3

Flex

ActionScript 3