hi,
there are 2 possibilities in blk.corruption cases
1. the corrupt blocks do not belong to any object(which is what u have told.
2. the corrupt blocks belong to a database object
if the blocks would have been of a db object it would not have been much of a bother to u, all u would have to do was to drop the object and restore it from uer backup or take any other route to get back uer data, which is pretty well documented, but since this is not uer case and that want to instruct oracle to forget that these blocks exist, then that would be asking for a lot, since these things are internal to the oracle kernel, we would have no way of controlling how oracle would pick blocks at its discretion, hence your only fallback is to get in touch with oracle support and sort out uer problem
cheers
soren