Forward Traffic to a captive portal.

Hello,

I need some help about the following. I've got a remote captive portal on a Datacenter. The agency and the datacenter are connected through the Fortigate via VPN IPSec. What I wanted to do is to route all the traffic from my agency subnet to the captive portal. I tried it with policy route but it doesn't seems to work. I wanted to do the same things with VIP but it doesn't allow me to nat the 0.0.0.0 subnet .

I hope to hear you soon.