BitmapData's threshold like function

hello,
i want to load 2 swf files, one with images(as background) and one with text(over the prev)
now i want from the text one to show only text, not it’s background too, so i am using

img2.threshold(img1, img1.rectangle, img1.rectangle.topLeft, ">=", 0x00FFFFFF, 0x00000000, 0x00FFFFFF,true)

where img1 is

igm1.draw(text_mc)

this wipes all the white pixels from the image(white is the background of the text swf) and displays exactly as i want.

but there is a problem, the text mc is no longer vector but bitmap so it looses quality at zoom.

my question is: can i apply something like this to a movieclip? and if yes how.

thanks.