restricting MSN Messenger, Yahoo Messenger, and POP3 access

I have a Cisco PIX 515 in my network. I want to restrict MSN and
Yahoo Messenber to my local area network only. I want my users to be
able to chat internally, but not with anyone outside of my firewall.

I also have users that have set their email client (Outlook Express)
to POP to their personal ISP to retrieve their email. Our WWW/Email
server is outside of the PIX and has a valid Internet IP address. I
want to restrict TCP port 110 access to only the IP of our mail
server.

PC's on my network pull a DHCP address of 10.10.x.x and a subnet of
255.255.0.0. These 10.10.x.x addresses get translated at the PIX and
grab a valid IP Internet address from our class c pool of global
addresses on the PIX.

Are these things possible? Any help is greatly appreciated.

Thanks,
Donald