To integrate some more rules for Spamassassin we have to create two files and import three keys. First you can read these links if you want. I'll just show you the short way.
RuleUpdates Spamassassin Wiki
Openprotect.com
SpamAssassin Rules Emporium (SARE)
http://daryl.dostech.ca/sa-update/sare/sare-sa-update-howto.txt

First create an Directory /etc/spamassassin/sa-update-files and jump into it.

mkdir /etc/spamassassin/sa-update-files

cd /etc/spamassassin/sa-update-files

Then download the pub.gpg file from Openprotect.com and rename it.

wget http://saupdates.openprotect.com/pub.gpg -O saupdates.openprotect.com.pub.gpg

Import it into GPG and sa-update.

gpg --import saupdates.openprotect.com.pub.gpg

sa-update --import saupdates.openprotect.com.pub.gpg

Now download the pub.pgp from daryl.dostech.ca and import it too.

wget http://daryl.dostech.ca/sa-update/sare/GPG.KEY -O daryl.dostech.ca.pub.gpg

gpg --import daryl.dostech.ca.pub.gpg

sa-update --import daryl.dostech.ca.pub.gpg

Cause i can't remember where i got this file you will have to get it from here.
spamassassin.pub.pgp

wget http://open.nshare.de/wiki/_media/setup/spamassassin.pub.pgp

gpg --import spamassassin.pub.pgp

sa-update --import spamassassin.pub.pgp

Then you have to create a file sa-update-channels.chan with following content:

/etc/spamassassin/sa-update-files/sa-update-channels.chan

updates.spamassassin.org 
70_sare_stocks.cf.sare.sa-update.dostech.net 
70_sare_adult.cf.sare.sa-update.dostech.net 
70_sare_spoof.cf.sare.sa-update.dostech.net 
70_sare_bayes_poison_nxm.cf.sare.sa-update.dostech.net 
70_sare_genlsubj_x30.cf.sare.sa-update.dostech.net 
70_sare_oem.cf.sare.sa-update.dostech.net 
70_sare_random.cf.sare.sa-update.dostech.net 
70_sare_specific.cf.sare.sa-update.dostech.net 
70_zmi_german.cf.zmi.sare.sa-update.dostech.net 
70_sare_evilnum0.cf.sare.sa-update.dostech.net 
70_sare_highrisk.cf.sare.sa-update.dostech.net 
70_sare_header0.cf.sare.sa-update.dostech.net 
70_sare_html0.cf.sare.sa-update.dostech.net 
70_sare_obfu0.cf.sare.sa-update.dostech.net 
70_sare_stocks.cf.sare.sa-update.dostech.net 
70_sare_unsub.cf.sare.sa-update.dostech.net 
70_sare_uri0.cf.sare.sa-update.dostech.net 
70_sare_uri1.cf.sare.sa-update.dostech.net 
70_sare_uri3.cf.sare.sa-update.dostech.net 
70_sc_top200.cf.sare.sa-update.dostech.net 
72_sare_bml_post25x.cf.sare.sa-update.dostech.net 
99_sare_fraud_post25x.cf.sare.sa-update.dostech.net 
88_FVGT_Bayes_Poison.cf.sare.sa-update.dostech.net 
88_FVGT_Tripwire.cf.sare.sa-update.dostech.net 
88_FVGT_rawbody.cf.sare.sa-update.dostech.net 
88_FVGT_subject.cf.sare.sa-update.dostech.net 
saupdates.openprotect.com 
chickenpox.cf.sare.sa-update.dostech.net

And a file sa-update-keys.chan with:

/etc/spamassassin/sa-update-files/sa-update-keys.chan

856AA88A 
BDE9DC10 
5244EC45

Finally you just have to run this command:

sa-update --channelfile sa-update-channels.chan --gpgkeyfile sa-update-keys.chan -D