How to route userdir requests to different hosts?

["Rose, John B" <jbrose@xxxxxxx>]

Looking for a way to route requests for different users to different back end hosts behind a proxy of some sort 

For example ...

http request to ...

http://abc.com/~user1

always goes to one specific host

an http requests to ...

http://abc.com/~user2

always goes to a another specific host

Any suggestions appreciated

Thanks

John