Are you simply trying to check for attributes on builtins, or install attributes onto builtins? I'm not sure how you could apply an attribute to a builtin, but perhaps you could try something similar to what Hook::LexWrap does. First, alias the function (in this case, the builtin) to some anonyomous name, and then repoint the builtin's glob entry in the symbol table to some new closure (the closure would simply call the builtin with its new anonymous name). You could then apply attributes to the closure, and still call the builtin in the same way.

I might have missed the point, and if I have, could you explain in more depth what you are trying to do? :)