IPSec w/ firewall in middle

I'm trying to configure two 5505's for IPSec but there's another firewall in the middle. What must I do to the middle firewall, what ports to pass IPSec between my two endpoints?

What kind of firewall are you using?

ZiPPy

I believe it's an ASA 5510.

for IKE/Isakmp, you'll need UDP500 (or TCP500 is you choose to do IKE over TCP)
if you're using ESP you'll need IP protocol 50
if you're using AH you'll need IP protocol 51