Well, as long as your custom component doesn't use any spark or fx tags, it's a simple thing to copy and paste (with minor changes to the namespaces).
Another alternative might be to compile your component as a standalone swf and then use it as a sub-application of your main program (only thing I know that allows multi-versioning). You can read more about sub-applications here.
thanks for the link, e.
yes, that is exactly what I would be doing -- creating an SWF.
my application has a kind of plug-in architecture where it loads different SWFs based on the option the user chooses. Each SWF is pretty much self-contained, however, some do use common/shared custom components.