Eski roundcube yüklüyse kaldırmak için,

cd /usr/local/cpanel/base
rm -rf roundcube*
mysql -p -e 'drop database roundcube';
chattr -i /usr/local/cpanel/base/frontend/x/webmaillogin.html
chattr -i /usr/local/cpanel/base/webmaillogin.cgi
/scripts/upcp

Dosyaları indirip yükleyelim ve chmod ayarlarını yapalım,

cd /usr/local/cpanel/base
wget -O roundcube.tar.gz http://easynews.dl.sourceforge.net/sourceforge/roundcubemail/roundcubemail-0.1beta2.1.tar.gz
tar -zxvf roundcube.tar.gz
rm -rf roundcube.tar.gz
mv -f roundcubemail-0.1beta2 roundcube
cd roundcube
chmod -R 777 temp
chmod -R 777 logs

Veritabanı oluşturmak ve sql yüklemek,

mysql -e "CREATE DATABASE roundcube;" -pDATABASEPASSWORD
mysql -e "use roundcube; source SQL/mysql.initial.sql;" -pDATABASEPASSWORD

dosya isimlerini değiştirelim,

cd config
mv db.inc.php.dist db.inc.php
mv main.inc.php.dist main.inc.php

db.inc.php dosyasını açalım,
nano db.inc.php
Arama yapalım,

$rcmail_config['db_dsnw'] = 'mysql://roundcube ass@localhost/roundcubemail';

Bunla değiştirelim,

$rcmail_config['db_dsnw'] = 'mysql://root ATABASEPASSWORD@localhost/roundcube';

main.inc.php dosyasını açalım,
nano main.inc.php

Arama yapalım,

$rcmail_config['default_host'] = '';

Bunla değiştirelim,

$rcmail_config['default_host'] = 'localhost';

Now we have to configure cPanel to show roundcube in the theme. Please note this is for the X theme(default) only!! If you use another theme please skip the next part and see below.

cd /usr/local/cpanel/base/roundcube/skins/default/images/
cp roundcube_logo.png /usr/local/cpanel/base/frontend/x/images/roundcube_logo.png
cp roundcube_logo.png /usr/local/cpanel/base/webmail/x/images/roundcube_logo.png
wget http://www.hostgeekz.com/files/hostgeekz/HGpatch-roundcube-1.0BETA2.1
patch -p0 < HGpatch-roundcube-1.0BETA2.1

**NOTE** If you receive a message stating
Reversed (or previously applied) patch detected! Assume -R?
please press N for No as this is because you previously installed roundcube

This will auto do all the necessary changes to roundcube and the X theme.
Once the patch is executed you may now access roundcube via http://yourip/webmail
If you do not use the X theme please do the following

wget http://www.hostgeekz.com/files/hostgeekz/HGpatch-roundcube-NON-X-1.0BETA2.1
patch -p0 < HGpatch-roundcube-NON-X-1.0BETA2.1

Then open your webmaillogin.html, please replace YOURTHEME with the name of your theme.

nano /usr/local/cpanel/base/frontend/YOURTHEME/webmaillogin.html

and find

</td>
</cpanelif>
</cpanelfeature>

Add Below

<td align="center" valign="bottom" width="200">
<a href="/roundcube/index.php"><img src="images/roundcube_logo.png" border="0"></a>
<a href="/roundcube/index.php">RoundCube</a>
</td>

***UPDATE***
Remember to chattr +i the files or add the patch to your /scripts/upcp.
chattr +i /usr/local/cpanel/base/frontend/x/webmaillogin.html
chattr +i /usr/local/cpanel/base/webmaillogin.cgi
That's it! You may now access roundcube via http://yourip/webmail