Hi,
By default, the answer is no. The reason for this is because EIGRP uses multicast packets to talk to other EIGRP enabled neighbors. The problem with this is that the PIX will not pass multicast packets. So, to get around this, you have a few choices.
1) you can configure a GRE tunnel between the 2 routers and pass your routing updates through this tunnel. On the PIX, you simply need to create the xlate and allow GRE to pass via your ACL. Be careful not to put all of your traffic between the these 2 routers in the GRE tunnel though. If you do this, you pretty much negate the need for a firewall.
2) you can configure the routers to send unicast packets to their neighbors by using the "neighbor" command on the routers. You will again need to create the xlate and allow EIGRP packets (in this case) to pass through the PIX ACL's. One caution here is that you may run into some ARP issues since the 2 routers will not be on the same subnet (a requirement for using the neighbor command).
Hope this helps.
Scott
