At the moment there is no clear procedure for any ISP to follow to even get a best guess as to whether an advertisement should be accepted or not.
What about requiring that a route appear in an RIR database period? Maybe that would be a good start. It's easy enough to do but virtually no one seems to do it. We've seen how lengthy The CIDR Report's list of unregistered (but nonetheless advertised) routes is -- why are these advertisements being accepted? This doesn't directly address hijacking, but it seems to me that there's no reason to spend time looking for old, unused, potentially hijackable address blocks if just about any ISP out there will accept your announcements of blocks that aren't even allocated. (Note: I'm not talking about IANA Reserved space.)