DMS integration with OpenERP

Hi, I need to develop a integration between any DMS and OpenERP, Alfresco has the options I need, but they are very simple so, any will do it. The key of this integration is that I need a one to several integration, so, one DMS instance will manage (contact to) several (has to be planned for hundreds or thousands) OpenERP databases. The integration will be for only a few documents, tax related, as it will be for e-billing, so, only one type of document (xml) is mandatory. The DMS has to be open source and the more open, the better. I need at least two different values, one for the development and one for the support hour as it will be a long term contract, the development will be the first step, but the support will be for years. If needed, I'll need the price for the instalation and configuration. Thanks for your quotation.