I am answering my own post for the benefit of those who might have had the same question... I just installed libfreetype6 from the PLF repository, and that was it.
On my screen, this actually turned things to a worse - fonts became sharper, but thinner and harder to read. It also turned out that the change could not be reversed... unless you are willing to take risk

Download libfreetype6 rpm from the Mandriva repository, then as root
CODE
#rpm -i --force libfreetype6-2.3.5-2mdv2008.0.i586.rpm
This will install Mandriva's version of libfreetype6 alongside with that from PLF. Now you can uninstall the PLF version in a usual way via MCC or urpmi. This will leave only libfreetype6-2.3.5-2mdv2008.