Applying firewalls to a mirrored port

Hey all,
I have a 750 board, and am mirroring ether2 to ether5.
What I want to do now is firewall ether5 so that I can filter what traffic goes to my tap.
I am well practiced in filter rules on the forward chain, but it seems the only way I can “catch” traffic on ether5 is in the pre-routing or input chain.
So, I just wanted to check - can I firewall a mirrored port? If I can, can you give me basic examples of how to catch all traffic for that ethernet port? I can figure out the rest from there.
Any help or answers would be most appreciated, so if all you have is a guess please let me know your thoughts.
Thanks,