You topology could look something like this.

Ok now I think I am getting it a bit more.  Sounds like although your 4500 switch is capable of routing there is no need for it to do much.  So let's keep it simple.  Have the 4500 switch downstream from new ASRs point a default route at the VIP addr...

I've read your post a few times over and am having troubles visualizing what you are trying to convey.  Can you post a quick diagram?