Actually it does not install OpenOffice in /var, it just downloads packages in the /var/cache directory before installing them. Instead of messing up your partitions, I suggest to download packages in a different location, then install them from this local directory. To do this you can try
Code:
yumdownloader --resolve --destdir /path/to/dir openoffice
the yumdownloader utility comes with the package yum-utils, which is not installed by default. The command above downloads openoffice and all its dependencies (see --resolve) in the directory specified by the --destdir option. Chose an appropriate location where you have enough space and the trick is done.
When you have packages stored in a local directory, you can tell yum to install from there:
Code:
yum localinstall /path/to/dir/*.rpm
Anyway, the size of 741 Mb looks huge to me. The core OpenOffice package is about 80 Mb, where the other 660 Mb come from?