How to create the fake package to replace/remove/update packages

Hi everybody.

I am battling with this issue for a long time, but never found the time 
to ask for help.

I am maintaining repository for CentOS 5.x with amongst other things a 
OpenOffice 3.x packages. I unpacked them to repository folder and then 
created fake packages that pull all necessary packages . ooo3-base pulls 
common packages and ooo3-en-US for example pulls language specific packages.

I first run into problem when I wanted to easily replace old OpenOffice 
2.x packages with OOO 3.1.1 buy adding Obsoletes: …. into spec file, but 
I am not able to force yum do remove OpenOffice 2.x packages.

Now OOO has changed packages from
    ooobasis3.1-base-3.1.1-9420.x86_64.rpm
to
    ooobasis3.2-base-3.2.0-9483.x86_64.rpm
(note the change in package name from 3.1 to 3.2, so there is no clear 
update path.

Yum version is yum-3.2.22-20.el5.centos.

Is there anything to add to spec file of the fake package so packages 
named openoffice3.1- would be updated with openoffice3.2- counterparts? 
Or at least to force yum to automatically remove older version prior to 
installation of the new version?

Ljubomir Ljubojevic