PBR would be the way so that the host would use that link.
Please ensure that check the Limitations listed on that SK article.
Basically once use more then the Firewall Blade then PBR is not supported.
If need to use the Blades that not supported with PBR then could
1.) Use a Proxy Server and configure so that is on a Network that leads off via ISP-2. Any other host needing to use ISP-2 would use that Proxy Server as well. Static Route to Internal Network and then DG the ISP-2 Router
2.) Use VSX and use a seperate VS that connects to ISP-2 for the Traffic from the Host, ie VSX would have a Static Route for the Internal Network and Default Gateway via ISP-2. Any Hosts that need to use ISP-2 would have to connect via that seperate VS to be routed out via ISP-2
3.) If have known targets then can simply static route those destinations via ISP-2, useful for VPN targets, Backup Solutions, MessageLabs mail where have known hub IP to use.
All have certain limitations however with the information provided then the best that can answer.