I'm not aware of anything that describes what you're after.
In a nutshell - firewall rules affect what can go where, except in cases where the traffic is redirected to a local daemon, because the traffic is then sourced from the firewall itself and your rules do not apply in that case.
I'd like to see an additional tab in the firewall rules page for traffic from localhost to other destinations, which would remove this limitation. Maybe something we'll see in a future release.