[exim] Need help integrating spamassassin

First off, let me apologize for asking this question. If I was better
at RTFM I'm sure I wouldn't have to ask this here. That, and you all
probably get asked this question all the time. Can anyone point me to a
friendly, easy-to-understand guide for integrating spamassassin with
exim? Here's my info:

Gentoo system running kernel 2.6.19-gentoo-r5 SMP

baby ~ # emerge -pv spamassassin exim

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild R ] mail-filter/spamassassin-3.1.8-r1 USE="berkdb doc mysql
ssl -ipv6 -ldap -postgres -qmail -sqlite -tools" 980 kB
[ebuild R ] mail-mta/exim-4.67 USE="exiscan exiscan-acl ldap mysql
pam perl sasl ssl tcpd -X -dnsdb -domainkeys -dovecot-sasl -gnutls -ipv6
-lmtp -mailwrapper -mbox -mbx -nis -postgres -radius -spf -sqlite -srs
-syslog" 0 kB

Please help!