Solved this problem using this contrib : ?topic=43988.new;topicseen#new
You can have ocs running under php4 and glpi running under php5.. The important thing is to configure the ebay used by glpi to use php5 ot to configure the opt/? directory used as stated in the howto..
One crucial point is to restore the rights of the directories EXACTLY as they were with 0.68.x ..
Works fine for me now.