ProxyPass 302 redirect possible?

Proxypass does not include redirect functionality that you can use for this. It only modifies traffic on the way to the server.

Your better off adding an iRule to do it.

when HTTP_REQUEST {
  if {[class search myclass equals "[HTTP::host][HTTP::uri]"]} {
    HTTP::redirect [class search -value myclass equals "[HTTP::host][HTTP::uri]"]
  }
}

Then class myclass should contain text of the form...

Key              Value
old.host.com/url http://new.host.com/newurl
old.host.com/url http://new.host.com/
old.host.com/url /mynewurl