The way the IK deform happens teh actual model is not changed but a copy of it. so there is probably no way to do what you expect, because the original model never changes and that's what the relative vertex keying uses. This is not to say it couldn't be a future feature.. Might be possible with python though..
You can use two scripts that JMS did. ApplyArmature and Copy RVK for that. I don't have the links, sorry, but if you look for them over at elyusiun, you'll find them.
Martin
Life is what happens to you when you're busy making other plans.
- John Lennon