No loadbalancer does url rewrite.
However, you can intercept some url and create an http redirect to a different location.
For example you can create a url match to catch /vista/* requests and create a redirect service to /webct/%p.
There is an example on how to configure redirect at :
http://www.cisco.com/en/US/products/hw/modules/ps2706/products_configuration_example09186a00802877f6.shtml
The result would be exactly what you need.
The client will be transparently redirected to the correct page.
The only difference is that the client will be able to see the correct url.
Gilles.