Just a linkdump, because my wrist is still broken:
We needed a external font library for a project that we did. Here are two links to useful information:
(Runtime font loading with AS3 / Flash CS3 (not Flex!))
There is just one thing that could drive you mad:
If you additionally place a static textfield onto the stage with the same font the text in the dynamic textfield isn’t shown anymore. Don’t really understand why…but it’s probably the same problem as if you set the same font in the dynamic textfield (maybe a “font collision”?). A workaround is to create the font symbol in the fla and select it (the one with *) in the property inspector.
We used another approach, we removed every font used in the external font-library from the fla-library, and because the libraries can get big, I found this script that will make it easier: