Welcome!
You can see
here what the changes are. I don't believe you can just 'update', but rather need a new install. I might be wrong though. Out of habit I always use the localized version straight from the source at
www.openoffice.orgIt's pretty easy if you know what you're doing.
Download to Desktop
Extract
Navigate to ~/Desktop/OOo_2.3.1dir/RPMS
Remove all unneeded rpm's (self evident, you don't need gnome integration for example)
Navigate to ~/Desktop/OOo_2.3.1dir/RPMS/desktop_integration
Remove all, except for Slackware_integration
Copy Slackware_integration to ~/Desktop/OOo_2.3.1dir/RPMS
Now fire up Konsole. Su to root
Navigate to ~/Desktop/OOo_2.3.1dir/RPMS
Type this:
rpm2tgz *rpm
installpkg *tgz
You can now safely remove the OOo directory from your desktop.
Done!
You can safely remove 2.2 with your favorite package manager, or let it sit until you are comfortable that it was a good idea to make the switch. They wont bite each other.