...
setFontStyle("courier", 10, "Courier New", SWT.NORMAL);
...

// transcript is the StyledText
public void setFontStyle(String description, int point, String font, int style) {
		if (transcript == null || display == null) return;
		
		if (fontRegistry == null)
			fontRegistry = new FontRegistry(display);
		
		fontRegistry.put(description, new FontData[] {new FontData(font, point, style)});
		transcript.setFont(fontRegistry.get(description));
		transcript.update();
	}