Download sms.openbravo.sh to a clean folder and run it.
It will download and install all the required packages and will set permissions, start services and will ask you to choose the password for postgres user.
After the script end you only need to logout and login and start tomcat with the command
/etc/rc.d/rc.tomcat start
Afterwards start the OpenBravo Installer.
./OpenbravoERP-2.35-linux-installer.bin

Prefix dirs are

java = /usr/lib/jdk
ant = /usr/lib/ant
tomcat = /usr/share/tomcat
psql-bin = /usr/bin

Required PAckages:

----------------------------------------------------------------------------------------
\openbravo\ (6)                       276 276 008 2007-09-22 15:41 -----
----------------------------------------------------------------------------------------
OpenbravoERP-2.35-linux-installer.bin                 144 731 612 2007-09-20 23:37 -a---
apache-ant-1.7.0-i586-bj.tgz                            3 323 873 2007-09-20 23:37 -a---
jdk-6u2-i586-2.tgz                                     80 907 534 2007-09-20 23:37 -a---
jre-6u2-i586-1.tgz                                     34 051 950 2007-09-20 23:37 -a---
postgresql-8.2.4-i686-1mfb.tgz                          7 380 224 2007-09-20 23:37 -a---
tomcat-5.5.16-noarch-1stb.tgz                           5 879 458 2007-09-20 23:37 -a---



Rest of the Packages can be downloaded manually, just comment '#' or remove wget lines on script.

http://heanet.dl.sourceforge.net/sourceforge/openbravo/OpenbravoERP-2.35-linux-installer.bin
http://slackware.cs.utah.edu/pub/slackware/slackware-12.0/extra/jdk-6/jdk-6u2-i586-2.tgz
http://slackware.cs.utah.edu/pub/slackware/slackware-12.0/patches/packages/jre-6u2-i586-1.tgz