Hello,
I want to register an AS2 class to an object that doesn't have a linkage
identifier. Is there a way to set the linkage identifier at runtime? or how can
i register a class to an object that doesn't have linkage identifier?
or could i extend the movieclip class globaly? so every instance of the
movieclip have the extended new clas on it, with out the need to set this for
each object?

Thanks!

No way to set linkage at runtime.

The only way to link a class to an object then would be to use the old AS1
prototype way.

MovieClip.prototype.myFunction = function() etc...

There's no other way to extend the built-in classes using only AS2.

Check out Colin Mook's ActionScript book, explains all that prototyping stuff
really well - by far the best AS book ever written, only covers AS1 for now but
90% of it is still applicable with AS2.