is possible to intercept (before writeú all instance variable writes on every existing objects?

I found a discussion here: http://forum.world.st/Is-it-possible-to-follow-an-object-through-a-computati...

Known solutions: .... 3) Metalinks - it's based on intercepting method calls, right? But I need to intercept direct instance variable write, so probably not possible

Ok, I learned more about MetaLinks and it's perfectly possible to intercept instance variable writes via. installing MetaLink into object instance (cool) - then I can intercept instvar write, but one problem immediately occurs: when installing MetaLink into object instance, an original object class is exchanged to anonymous subclass of the original class - and because typical #= method is implemented like: = self == anObject ifTrue: [ ^ true ]. self class = anObject class ifFalse: [ ^ false ]. ... then most of #= comparisons in application logic is broken due to "self class = anObject class" part. Is there any way to solve this problem? Thanks! pf